Journal articles: 'Photoconductivity - Nanostructures'

1

Ruda, H., and A. Shik. "Ballistic photoconductivity in nanostructures." Applied Physics Letters 78, no. 18 (April 30, 2001): 2778–80. http://dx.doi.org/10.1063/1.1368372.

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Chen, Cheng-Ying, Ming-Wei Chen, Jr-Jian Ke, Chin-An Lin, José R. D. Retamal, and Jr-Hau He. "Surface effects on optical and electrical properties of ZnO nanostructures." Pure and Applied Chemistry 82, no. 11 (August 6, 2010): 2055–73. http://dx.doi.org/10.1351/pac-con-09-12-05.

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This article presents a comprehensive review of the current research addressing the surface effects on physical properties and potential applications of nanostructured ZnO. Studies illustrating the transport, photoluminescence (PL), and photoconductivity properties of ZnO with ultrahigh surface-to-volume (S/V) ratio are reviewed first. Secondly, we examine recent studies of the applications of nanostructured ZnO employing the surface effect on gas/chemical sensing, relying on a change of conductivity via electron trapping and detrapping process at the surfaces of nanostructures. Finally, we comprehensively review the photovoltaic (PV) application of ZnO nanostructures. The ultrahigh S/V ratios of nanostructured devices suggest that studies on the synthesis and PV properties of various nanostructured ZnO for dye-sensitized solar cells (DSSCs) offer great potential for high efficiency and low-cost solar cell solutions. After surveying the current literature on the surface effects on nano-structured ZnO, we conclude this review with personal perspectives on a few surface-related issues that remain to be addressed before nanostructured ZnO devices can reach their ultimate potential as a new class of industrial applications.

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Mishra, Sheo K., U. K. Tripathi, Saurabh Dixit, K. C. Dubey, and R. K. Shukla. "ZnO Nano-microstructures and their Photo Conducting Properties Synthesized by Sol-Gel Method." SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology 10, no. 02 (December 25, 2018): 95–98. http://dx.doi.org/10.18090/samriddhi.v10i02.3.

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In the present paper, photoconductivity (PC) of Zinc-oxide (ZnO) nanostructures synthesized by sol-gel method has been investigated. Structural study has been performed by X-ray diffraction (XRD) patterns. The XRD result confirms the formation of hexagonal phase. In the photoconductivity analysis, growth and decay of photocurrent of ZnO nanostructures have been investigated. The photo-response of prepared sample has been measured underUV illumination using thick film of powder without any binder. The growth and decay of photocurrent show fastrise and decay of photocurrent indicating suitability for UV photodetectors applications

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Susha, N., K. Nandakumar, and Swapna S. Nair. "Enhanced photoconductivity in CdS/betanin composite nanostructures." RSC Advances 8, no. 21 (2018): 11330–37. http://dx.doi.org/10.1039/c7ra13116j.

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The synthesis is described of inorganic/organic hybrid nanostructured composites based on CdS/betanin with enhanced photoconductivity due to the transfer of photogenerated electrons from the conduction band of betanin to the conduction band of CdS.

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Bayan, Sayan, Sheo K. Mishra, Purushottam Chakraborty, Dambarudhar Mohanta, Ravi Shankar, and Rajneesh K. Srivastava. "Enhanced vacuum-photoconductivity of chemically synthesized ZnO nanostructures." Philosophical Magazine 94, no. 9 (January 27, 2014): 914–24. http://dx.doi.org/10.1080/14786435.2013.869367.

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Gubin M.Yu., Dzedolik I. V., Prokhorova T. V., Pereskokov V. S., and Leksin A. Yu. "Switching effects in plasmon circuits based on thin metal films and nanostructures with increased photoconductivity." Optics and Spectroscopy 132, no. 3 (2022): 406. http://dx.doi.org/10.21883/eos.2022.03.53564.2700-21.

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The features of optical control of surface plasmon-polariton propagation in plasmon circuits based on thin metal waveguides and semiconductor nanostructures are considered. A model of a plasmon resonator with additional elements based on semiconducting materials exhibiting strong photoconductivity is proposed. By means of numerical simulation, the possibility of switching the surface plasmon-polariton flux in the plasmon circuit by switching on/off the external optical pumping field, which changes the contribution of light-induced conduction of control elements, is shown. Keywords: surface plasmon-polaritons, metal plasmon waveguide, photoconductivity, plasmon resonator.

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Huang, Y. H., R. S. Chen, J. R. Zhang, and Y. S. Huang. "Electronic transport in NbSe2two-dimensional nanostructures: semiconducting characteristics and photoconductivity." Nanoscale 7, no. 45 (2015): 18964–70. http://dx.doi.org/10.1039/c5nr05430c.

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Yin, Z. G., X. W. Zhang, Z. Fu, X. L. Yang, J. L. Wu, G. S. Wu, L. Gong, and Paul K. Chu. "Persistent photoconductivity in ZnO nanostructures induced by surface oxygen vacancy." physica status solidi (RRL) - Rapid Research Letters 6, no. 3 (January 19, 2012): 117–19. http://dx.doi.org/10.1002/pssr.201105551.

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Chitara, Basant, Amit K. Shringi, Biswadev Roy, Marvin H. Wu, and Fei Yan. "Facile synthesis and morphology-induced photoconductivity modulation of Bi2O2S nanostructures." Materials Letters 346 (September 2023): 134545. http://dx.doi.org/10.1016/j.matlet.2023.134545.

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Sprincean, Veaceslav, Liviu Leontie, Iuliana Caraman, Oleg Lupan, Rainer Adeling, Silviu Gurlui, Aurelian Carlescu, Corneliu Doroftei, and Mihail Caraman. "Preparation, Chemical Composition, and Optical Properties of (β–Ga2O3 Composite Thin Films)/(GaSxSe1−x Lamellar Solid Solutions) Nanostructures." Nanomaterials 13, no. 14 (July 11, 2023): 2052. http://dx.doi.org/10.3390/nano13142052.

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GaSxSe1−x solid solutions are layered semiconductors with a band gap between 2.0 and 2.6 eV. Their single crystals are formed by planar packings of S/Se-Ga-Ga-S/Se type, with weak polarization bonds between them, which allows obtaining, by splitting, plan-parallel lamellae with atomically smooth surfaces. By heat treatment in a normal or water vapor-enriched atmosphere, their plates are covered with a layer consisting of β–Ga2O3 nanowires/nanoribbons. In this work, the elemental and chemical composition, surface morphology, as well as optical, photoluminescent, and photoelectric properties of β–Ga2O3 layer formed on GaSxSe1−x (0 ≤ x ≤ 1) solid solutions (as substrate) are studied. The correlation is made between the composition (x) of the primary material, technological preparation conditions of the oxide-semiconducting layer, and the optical, photoelectric, and photoluminescent properties of β–Ga2O3 (nanosized layers)/GaSxSe1−x structures. From the analysis of the fundamental absorption edge, photoluminescence, and photoconductivity, the character of the optical transitions and the optical band gap in the range of 4.5–4.8 eV were determined, as well as the mechanisms behind blue-green photoluminescence and photoconductivity in the fundamental absorption band region. The photoluminescence bands in the blue-green region are characteristic of β–Ga2O3 nanowires/nanolamellae structures. The photoconductivity of β–Ga2O3 structures on GaSxSe1−x solid solution substrate is determined by their strong fundamental absorption. As synthesized structures hold promise for potential applications in UV receivers, UV-C sources, gas sensors, as well as photocatalytic decomposition of water and organic pollutants.

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Ekiz, Okan Öner, Koray Mizrak, and Aykutlu Dâna. "Chemically Specific Dynamic Characterization of Photovoltaic and Photoconductivity Effects of Surface Nanostructures." ACS Nano 4, no. 4 (April 9, 2010): 1851–60. http://dx.doi.org/10.1021/nn9014196.

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Avouris, Phaedon. "Carbon Nanotube Electronics and Optoelectronics." MRS Bulletin 29, no. 6 (June 2004): 403–10. http://dx.doi.org/10.1557/mrs2004.123.

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AbstractCarbon nanotubes (CNTs) are one-dimensional nanostructures with unique properties. This article discusses why CNTs provide an ideal basis for a future carbonbased nanoelectronic technology, focusing specifically on single-carbon-nanotube fieldeffect transistors (CNT-FETs). Results of transport experiments and theoretical modeling will be used to address such issues as the nature of the switching mechanism, the role of the metal contacts, the role of the environment, the FET scaling properties, and the use of these findings to produce high-performance p-type, n-type, and ambipolar CNT-FETs and simple intra-nanotube circuits. CNTs are also direct-gap nanostructures that show promise in the field of optoelectronics. This article briefly reviews their optical behavior and presents results that show that ambipolar CNT-FETs can be used to produce electrically controlled light sources based on radiative electron–hole recombination. The reverse process—that is, the generation of photocurrents by the irradiation of single CNT—FETs—and photoconductivity spectra of individual CNTs are also demonstrated.

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Beinik, Igor, Markus Kratzer, Astrid Wachauer, Lin Wang, Yuri P. Piryatinski, Gerhard Brauer, Xin Yi Chen, Yuk Fan Hsu, Aleksandra B. Djurišić, and Christian Teichert. "Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM." Beilstein Journal of Nanotechnology 4 (March 21, 2013): 208–17. http://dx.doi.org/10.3762/bjnano.4.21.

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Background: ZnO nanostructures are promising candidates for the development of novel electronic devices due to their unique electrical and optical properties. Here, photoconductive atomic force microscopy (PC-AFM) has been applied to investigate transient photoconductivity and photocurrent spectra of upright-standing ZnO nanorods (NRs). With a view to evaluate the electronic properties of the NRs and to get information on recombination kinetics, we have also performed time-resolved photoluminescence measurements macroscopically. Results: Persistent photoconductivity from single ZnO NRs was observed for about 1800 s and was studied with the help of photocurrent spectroscopy, which was recorded locally. The photocurrent spectra recorded from single ZnO NRs revealed that the minimum photon energy sufficient for photocurrent excitation is 3.1 eV. This value is at least 100 meV lower than the band-gap energy determined from the photoluminescence experiments. Conclusion: The obtained results suggest that the photoresponse in ZnO NRs under ambient conditions originates preferentially from photoexcitation of charge carriers localized at defect states and dominates over the oxygen photodesorption mechanism. Our findings are in agreement with previous theoretical predictions based on density functional theory calculations as well as with earlier experiments carried out at variable oxygen pressure.

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Bogdanov, E. V., and N. Ya Minina. "Concentration and Mobility of Electrons in n-GaAs/AlGaAs:Si Nanostructures under Uniaxial Compression in the Dark and After Illumination." International Journal of Nanoscience 18, no. 03n04 (March 26, 2019): 1940028. http://dx.doi.org/10.1142/s0219581x19400283.

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Resistivity, Hall effect and quantum oscillations of magnetoresistance in a two-dimensional electron system at an n-GaAs/Al0.29Ga0.71As:Si heterointerface have been investigated under uniaxial compression up to 3.5 kbar along [110] direction in the dark and after illumination by infrared diode at 1.7 K. The observed persistent photoconductivity is connected with the excitation of deep DX centers in the active layer. The electron redistribution between the quantum well and the active layer explains pressure dependence of the electron mobility and concentration fixed after illumination.

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Shih, H. Y., Y. T. Chen, N. H. Huang, C. M. Wei, and Y. F. Chen. "Tunable photoluminescence and photoconductivity in ZnO one-dimensional nanostructures with a second below-gap beam." Journal of Applied Physics 109, no. 10 (May 15, 2011): 103523. http://dx.doi.org/10.1063/1.3590152.

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Koyanagi, Emi, and Takashi Uchino. "Evolution process of luminescent Si nanostructures in annealed SiOx thin films probed by photoconductivity measurements." Applied Physics Letters 91, no. 4 (July 23, 2007): 041910. http://dx.doi.org/10.1063/1.2764441.

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17

Мынбаев, К. Д., Н. Л. Баженов, А. М. Смирнов, Н. Н. Михайлов, В. Г. Ремесник, and М. В. Якушев. "Оптические и структурные свойства твердых растворов HgCdTe с большим содержанием CdTe." Физика и техника полупроводников 54, no. 12 (2020): 1302. http://dx.doi.org/10.21883/ftp.2020.12.50229.9497.

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This work presents the results of studying the optical transmission, photoconductivity, photoluminescence, and X-ray diffraction of HgCdTe solid solution samples with a high (molar fraction 0.7–0.8) CdTe content, grown by molecular beam (MBE) and liquid-phase (LPE) epitaxy. It was shown that the studied material had a significant degree of disordering of the solid solution, which was greater in structures grown by MBE on GaAs substrates than in films grown by LPE. Photoluminescence studies have revealed states in the band gap, which were previously considered not typical of HgCdTe films grown on GaAs substrates, but only of films grown on Si. On the whole, the high quality of the material with a high CdTe content, grown by MBE and used to create the currently widely demanded HgTe / HgCdTe nanostructures, was confirmed.

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Farooqi, Mohd Mubashshir Hasan, and Rajneesh K. Srivastava. "Enhanced UV–vis photoconductivity and photoluminescence by doping of samarium in ZnO nanostructures synthesized by solid state reaction method." Optik 127, no. 8 (April 2016): 3991–98. http://dx.doi.org/10.1016/j.ijleo.2016.01.074.

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Varonides, A. C. "Tunneling photoconductivity computations of multi-quantum well p-i (nano)-n photovoltaic nanostructures by means of the causal Green's function." Thin Solid Films 451-452 (March 2004): 393–96. http://dx.doi.org/10.1016/j.tsf.2003.11.017.

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Dileep, Naduvile Purayil, Lakshmi Kollenchery Puthenveettil, Stephen Nagaraju Myakala, and Manikoth Shaijumon. "Enhanced Electrocatalytic Activity for Hydrogen Evolution Reaction from Electrophoretically-Deposited BiSbSe₃ Nanoparticles." ECS Meeting Abstracts MA2022-02, no. 23 (October 9, 2022): 964. http://dx.doi.org/10.1149/ma2022-0223964mtgabs.

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For the development of renewable energy conversion and storage systems, it is vital to investigate earth-abundant, noble-metal-free, and highly efficient electrocatalysts for the hydrogen evolution process (HER). Platinum and other precious metals-based electrocatalysts show better HER activity in acidic conditions than other electrocatalysts due to their fast kinetics and lower Tafel slope.[1] However, because they are rare and costly, they are challenging to deploy in practical applications. As a result, there has been an ongoing search for low-cost and earth-abundant materials that may be used as an efficient alternative for platinum-based electrocatalysts, with the goal of developing more cost-effective and inexpensive H2 manufacturing processes. The layered 2D nanomaterials have sparked a lot of scientific attention because of their tremendous potential for both fundamental and practical investigations. Natural minerals of the group V-VI (V = Bi, Sb; VI = S, Se) have exceptional optical and electrical characteristics.[2] Because of their availability, low cost, and tunable characteristics, antimony/bismuth-based chalcogenides are garnering a lot of attention as potential candidates as electrocatalysts for acidic HER. We have shown an efficient and straightforward approach for the electrochemical exfoliation of BiSbSe3 nanostructures from the ball-milled BiSbSe3 sample; the process parameters were adjusted in terms of time and applied voltage. Furthermore, a simple and straightforward electrophoretic deposition process was used to synthesize BiSbSe3 nanoparticles from exfoliated BiSbSe3 nanostructures. A DC voltage was supplied between the two inert electrodes in an aqueous electrolyte for the electrophoretic deposition of BiSbSe3 nanostructures directly onto a gold substrate. Charged particles or sheets suspended in the electrolyte are activated to migrate toward the electrode and deposit when a voltage is applied. The BiSbSe3 nanoparticles were deposited onto the positive electrode because the exfoliated BiSbSe3 nanostructures in water had a negative zeta potential. BiSbSe3 nanostructures prepared through electrochemical exfoliation method are electrophoretically deposited onto the gold substrate to obtain BiSbSe3 nanoparticles, were investigated as active electrocatalysts for HER in 0.5 M H2SO4 solution using a three-electrode set up. The optimized BiSbSe3 catalyst (10V10M-Au-7.5) is identified as highly active HER activity, having a low overpotential of 72 mV @ 10 mA cm−2 and a low Tafel slope of 31.6 mV dec-1, which far better than the antimony/bismuth chalcogenide system and very close to the state-of-the-art Pt/C catalyst. We demonstrate that the electrocatalytic HER activity is enhanced by highly active edge sites, large available surface active sites, defects created and partial oxidization of material during electrodeposition, and a synergistic effect between BiSbSe3 and the substrate. References [1] N.P. Dileep, T.V. Vineesh, P. V Sarma, M. V Chalil, C.S. Prasad, M.M. Shaijumon, Electrochemically Exfoliated β-Co(OH)2 Nanostructures for Enhanced Oxygen Evolution Electrocatalysis, ACS Appl. Energy Mater. 3 (2020) 1461–1467. https://doi.org/10.1021/acsaem.9b01901. [2] J. Wang, H. Yu, T. Wang, Y. Qiao, Y. Feng, K. Chen, Composition-Dependent Aspect Ratio and Photoconductivity of Ternary (BixSb1–x)2S3 Nanorods, ACS Appl. Mater. Interfaces. 10 (2018) 7334–7343. https://doi.org/10.1021/acsami.7b17253. Figure 1

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Alireza, Heidari. "Effect of Photoconductivity Precursor Volume on Structural, Physical, Electrical and Optical Properties of Thin Layers of Cadmium Oxide (CdO) Nanostructures Produced Using Spray Pyrolysis Technique." International Journal of Membrane Science and Technology 8, no. 2 (December 9, 2021): 40–53. http://dx.doi.org/10.15379/2410-1869.2021.08.02.04.

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Thin layers of Cadmium Oxide (CdO) are produced over glassy substrate by spray pyrolysis technique with precursor volumes of 50, 75 and 100 (ml). FESEM images of samples show the formation of nanometric structures and structural characterization of them resulted from XRD spectroscopy indicate the formation of cubic polycrystalline structure in growing layers with preferred direction of (111). Evaluating the optical properties of samples show that optical band gap of layers is reduced from 3.6 to 3.4 (eV) by increasing the precursor volume and the optical absorption coefficient of samples is in UV region at about 105 (cm-1). Data analysis indicates that the produced sample in volume of 100 mL has the smallest penetration depth (smaller than 200 nm) in UV region. On the other hand, thin layers of Cadmium Oxide (CdO) with various volumes of Cadmium acetate solution (40, 50 and 70 ml) were deposited using spray pyrolysis technique over a glassy substrate. Samples were investigated using FESEM images, XRD and UV-Vis spectra as well as I-V characteristic. It was found that all samples were grew up with polycrystalline nanostructures along the preferred direction of (002). In addition, it was found that grew up sample in the volume of 50 (ml) are of optimum photoconductivity condition in visible range regarding optimum structural (largest crystallite size and lowest crystallite defect density) and optical (smallest band gap and highest light absorption) conditions.

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Koposova, Ekaterina A., Yuri E. Ermolenko, Andreas Offenhäusser, and Yulia G. Mourzina. "Self-assembly and photoconductivity of binary porphyrin nanostructures of meso -tetrakis(4-sulfonatophenyl)porphine and Co(III) meso -tetra(4-pyridyl)porphine chloride." Colloids and Surfaces A: Physicochemical and Engineering Aspects 548 (July 2018): 172–78. http://dx.doi.org/10.1016/j.colsurfa.2018.03.053.

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23

Винниченко, М. Я., И. С. Махов, Н. Ю. Харин, С. В. Граф, В. Ю. Паневин, И. В. Седова, С. В. Сорокин, and Д. А. Фирсов. "Фотопроводимость и поглощение инфракрасного излучения в квантовых ямах p-GaAs/AlGaAs." Физика и техника полупроводников 55, no. 8 (2021): 629. http://dx.doi.org/10.21883/ftp.2021.08.51127.03.

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The spectra of low-temperature impurity-assisted far and mid-infrared photoconductivity and absorption in nanostructure with multiple GaAs/AlGaAs quantum wells doped with acceptors are investigated. The experimentally obtained absorption and photoconductivity spectra correlate well with each other. According to the hole and acceptor state energy spectrum calculations the spectral features related to the optical hole transitions from the ground acceptor state to the delocalized states of valence subbands, to the excited acceptor states and to the delocalized states above the quantum well (photoionization) are identified in the absorption and photoconductivity spectra.

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Golikova, O. A. "Photoconductivity of nanostructured hydrogenated silicon films." Semiconductors 36, no. 6 (June 2002): 691–94. http://dx.doi.org/10.1134/1.1485672.

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Mousavi, M., and Sh Tabatabai Yazdi. "Photoconductivity in nanostructured sulfur-doped V2O5 thin films." Modern Physics Letters B 30, no. 09 (April 10, 2016): 1650151. http://dx.doi.org/10.1142/s0217984916501517.

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In this paper, S-doped vanadium oxide thin films with doping levels up to 40 at.% are prepared via spray pyrolysis method on glass substrates, and the effect of S-doping on the structural and photoconductivity related properties of [Formula: see text]-V2O5 thin films is studied. The results show that most of the films have been grown in the tetragonal [Formula: see text]-V2O5 phase structure with the preferred orientation along [200]. With increasing the doping level, the samples tend to be amorphous. The structure of the samples reveals to be nanobelt-shaped whose width decreases from nearly 100 nm to 40 nm with S concentration. The photoconductivity measurements show that by increasing the S-doping level, the photosensitivity increases, which is due to the prolonged electron’s lifetime as a result of enhanced defect states acting as trap levels.

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Dobrovolsky, A. A., Z. M. Dashevsky, V. A. Kasiyan, L. I. Ryabova, and D. R. Khokhlov. "Photoconductivity of oxidized nanostructured PbTe(In) films." Semiconductor Science and Technology 24, no. 7 (June 2, 2009): 075010. http://dx.doi.org/10.1088/0268-1242/24/7/075010.

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Bahishti, Adam A., and Abdul Majid. "Intensity Dependent Photoconductivity in ZnO Nanostructured Film." Advanced Nano Research 1, no. 1 (November 1, 2017): 23–30. http://dx.doi.org/10.21467/anr.1.1.23-30.

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RANI, MAMTA, and S. K. TRIPATHI. "SYNTHESIS AND PHOTOSENSITIVE PERFORMANCE OF NANOSTRUCTURED ZnO/DYE HYBRID FILM FOR ENERGY CONVERSION." International Journal of Modern Physics: Conference Series 22 (January 2013): 18–23. http://dx.doi.org/10.1142/s2010194513009872.

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The ZnO film prepared by doctor blade method are highly porous in presence of structure directing agent PEG and then can be easily sensitized by various molecules. In the present work, the nanostructured ZnO /dye hybrid film prepared by doctor blade method has been investigated in conductivity and photoconductivity measurements in view of applications in dye-sensitized solar cells (DSSC) and in optoelectronics, since electron transport in these devices plays a decisive role for the electron collection efficiency and therefore for the overall efficiency. The absorption of ZnO film sensitized by Rose Bengal dye (RB) has been studied by UV spectroscopy which indicates that after the dye is adsorbed on the ZnO electrode, its absorption spectra showed red-shift in the peak position compared to the absorbance spectra of dye in ethanol. Highly porous ZnO films are found to have high dark conductivity, probably because of a higher n-doping, which is due to higher concentration of Zn atoms in the film. On the other hand, ZnO /RB hybrid film is found to show a much higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and lower conductivity in the dark.

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Saibal, B., A. Z. Ashar, R. Nandini Devi, K. S. Narayan, and S. K. Asha. "Nanostructured Donor–Acceptor Self Assembly with Improved Photoconductivity." ACS Applied Materials & Interfaces 6, no. 21 (October 20, 2014): 19434–48. http://dx.doi.org/10.1021/am5055542.

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Bojorge, Claudia D., Mario F. Bianchetti, Horacio R. Cánepa, and Noemí Walsöe de Reca. "Photoconductivity Measurements in Nanostructured ZnO and ZnO:Al Films." Procedia Materials Science 8 (2015): 623–29. http://dx.doi.org/10.1016/j.mspro.2015.04.117.

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Hullavarad, Shiva, Nilima Hullavarad, David Look, and Bruce Claflin. "Persistent Photoconductivity Studies in Nanostructured ZnO UV Sensors." Nanoscale Research Letters 4, no. 12 (August 28, 2009): 1421–27. http://dx.doi.org/10.1007/s11671-009-9414-7.

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Saleh, Z. M., G. Nogay, E. Ozkol, G. Yilmaz, M. Sagban, M. Gunes, and R. Turan. "Atmospheric aging and light-induced degradation of amorphous and nanostructured silicon using photoconductivity and electron spin resonance." Canadian Journal of Physics 92, no. 7/8 (July 2014): 713–17. http://dx.doi.org/10.1139/cjp-2013-0573.

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Previous studies indicate that the dark conductivity in amorphous and microcrystalline silicon may increase or decrease with exposure to deionized water (DIW) or pure oxygen at 80 °C but always decreases with light exposure. While the light-induced effect is linked to paramagnetic dangling bonds (Do), the origin of metastability in microcrystalline silicon remains unclear. In this study, we use steady-state photoconductivity (SSPC), dual-beam photoconductivity (DBP), and electron spin resonance (ESR), to study the behaviors under soaking in DIW and (or) pure oxygen at 80 °C and light-exposure of amorphous (a-Si:H) and nanostructured (nc-Si:H) silicon samples deposited in a capacitively coupled plasma-enhanced chemical vapor deposition system. Powders from thick samples of low and high crystallinity (Xc) peeling off large substrates were collected in quartz tubes for ESR measurements. Dark conductivity decreases upon exposure to pure oxygen at 80 °C for nc-Si:H but remains unchanged for a-Si:H. The ESR signal attributed to Do decreases with soaking in DIW for high and low crystallinity nc-Si:H but the effect is more significant for higher Xc. Changes in SSPC, DBP, and ESR are used to compare the degradation mechanisms because of O2 exposure and light for amorphous and nanostructured silicon.

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Rambeloson, Jafetra, Qiliang Li, and Dimitris E. Ioannou. "(Invited, Digital Presentation) Photoactivated In₂O₃/GaN NW Sensors for Monitoring NO₂ with High Sensitivity and Low Power." ECS Meeting Abstracts MA2022-02, no. 36 (October 9, 2022): 1324. http://dx.doi.org/10.1149/ma2022-02361324mtgabs.

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We report and discuss our results on the performance of our photoactivated In3O2/GaN NW sensors, for monitoring NO2 at various levels of relative humidity and operating power. A 1ppm sensitivity as high as 29% was demonstrated at operating power of 5 mW and relative humidity 40%. Nanostructure-based semiconductor gas sensors such as nanowires, nanotubes or nanorods have seen significant progress in recent years, owning to their large surface-to-volume ratio proprieties, which lead to considerably increased sensitivity and improve the time response to analyte gases. In particular, Gallium Nitride (GaN) nanostructure-based gas sensors have generated a lot of interest due to its unique combination of sensor “friendly” properties such as, direct bandgap, excellent carrier mobility, high heat capacity and high breakdown voltage. These properties combined with suitable surface engineering make GaN and GaN-based nanostructures an excellent candidate for portable gas sensors. In this work, Gallium Nitride (GaN) nanowire (NW)-based NO2 sensors, functionalized with either pure In2O3 or In2O3 covered with an evaporated Au nanolayer, were developed for low operating power and high sensitivity. An AlGaN buffer layer was first deposited on a Si substrate to minimize lattice mismatch and improve adhesion between the Si substrate and the GaN NWs. Then the GaN NWs were patterned by stepper lithography-assisted dry-etching, followed by Induced Coupled Plasma etching using a metal hard mask to protect the GaN NW. The nanowire width target ranged between 200-600nm. Subsequently, electrodes composed of Ti/Al/Ti/Au metal stacks were deposited on top of the GaN to form Ohmic contacts. A thin In2O3 layer metal oxide receptor was deposited on all devices, using RF magnetron sputtering on top of the exposed GaN NW and this was followed for a subgroup of devices by coating the In2O3 with an evaporated Au nanolayer. Finally, rapid thermal annealing (RTA) at 700 0C was performed to crystalize the receptor layers and improve the ohmic contact. The surface quality of the resulting sensors was inspected with the help of Scanning Electron Microscope (SEM) micrographs. Several devices of each group (In2O3 and In2O3/Au ) were wire bonded and mounted onto an array board chamber. The devices were biased under 5V DC. Photoconductivity measurements, humidity testing and NO2 gas testing (1ppm and 10ppm concentration) were conducted. The sensors were illuminated under constant UV LED illumination throughout the duration of the testing at two wavelengths, 265 nm and 365 nm and three irradiance levels, 5mW, 30mW and 60mW. In general, the In3O2 GaN NW sensors where characterized by low sensitivity levels, whereas the In3O2/Au GaN NW sensors achieved excellent sensitivity levels. Fig.1 shows typical dynamic responses to 1ppm NO2 of the In3O2/Au GaN NW sensors under illumination at 265 nm and 365 nm, respectively, and Fig.2 the response at various relative humidity (RH) levels. An increase in resistance upon exposure to NO2 is observed, confirming the oxidizing nature of the NO2 gas. At this NO2 concentration level, the highest response value (29%) was obtained under (5mW, 265 nm) illumination, whereas the sensitivity under (5mW, 365nm) illumination was lower. For (30mW, 265nm) illumination, the sensitivity was 23% and for (30mW, 365nm) illumination it dropped to 15%. This phenomenon has been observed in the past by other authors also, and although its origins are not yet understood unambiguously, it may be caused by a higher rate of phonon energy relaxation at the surface at higher wavelengths, thereby reducing the effectiveness of chemisorption at the surface. In conclusion, room-temperature low-power photoactivated In3O2/Au GaN NW sensors with excellent levels of sensitivity at elevated relative humidity were designed, fabricated and tested. Figure 1

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Franco, Alfredo, Víctor Rentería, Guadalupe Valverde-Aguilar, and Jorge A. García-Macedo. "Photoconductivity for Silver Nitrate in Nanostructured Sol–Gel Materials." Journal of Nanoscience and Nanotechnology 8, no. 12 (December 1, 2008): 6569–75. http://dx.doi.org/10.1166/jnn.2008.18427.

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We report on the photoconductive response of nanostructured sol–gel films in function of the silver nitrate concentration (ions and colloids). Silver colloids were obtained by spontaneous reduction process of Ag+ ions to Ag0. 2-d hexagonal nanosructured sol–gel thin films were prepared by dipcoating method using the non-ionic diblock copolymer Brij58 to produce channels into the film, which house the silver nanoparticles. An optical absorption band located at 430 nm was detected by optical absorption; it corresponds to the surface plasmon. A fit to this band with modified Gans theory is presented. Photoconductivity studies were performed on films with silver ions and films with silver colloids to characterize their mechanisms of charge transport in the darkness and under illumination at 420 and 633 nm wavelengths. The films with silver colloids exhibit a photovoltaic effect stronger than the films with silver ions. While a photoconductive behaviour is observed in the films with silver ions.

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FONSECA, LUIS F., OSCAR RESTO, GUILLERMO NERY, YURY POSADA, ZVI WEISZ, HUIMIN LIU, and AZIZ MAHFOUD. "OPTICAL AND ELECTRICAL PROPERTIES OF PURE AND RARE-EARTH-DOPED nc-Si/SiO2 COMPOSITES PREPARED BY RF COSPUTTERING." Surface Review and Letters 09, no. 05n06 (October 2002): 1655–60. http://dx.doi.org/10.1142/s0218625x02004165.

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Photoluminescence and optical absorption spectra from silicon nanoparticles embedded in SiO 2 are presented. The material was synthesized by RF cosputtering. The samples were prepared with a variety of Si volume concentrations and annealing temperatures. The results are discussed by correlating them with the preparation conditions, the nanostructure, and comparing them with the results obtained for porous silicon. The conductivity, photoconductivity and minority carriers diffusion length were also obtained for samples with different Si content and average size of the nanostructure. The study gives information about the percolation threshold and the electrical transport mechanisms in the composite. Eu- and Er-doped samples were finally prepared and studied for their PL response. A clear correlation between the enhancement of the Er +3 infrared emission and the presence of the silicon nanostructure is shown. In the case of Eu-doped samples, emissions from Eu +3 or Eu +2 are observed depending on the characteristics of the host (when exciting with 514.5 nm laser radiation). Degenerate four-wave mixing signals suggest a strong interaction between the free carriers of the silicon nanostructure and the Eu ions that can promote the emission from Eu +2 under illumination.

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36

Bartolomé, J., D. Maestre, A. Cremades, and J. Piqueras. "Indium Sulfide and Ternary In-S-O Nanowires for Optoelectronic Applications." Microscopy and Microanalysis 18, S5 (August 2012): 121–22. http://dx.doi.org/10.1017/s1431927612013268.

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Indium sulfide (In2S3) is a promising semiconductor material for window layers in solar cell devices and other optoelectronic applications as it presents a direct band gap around 2.0 eV at room temperature, and large photosensitivity and photoconductivity. The presence of several polymorphic structures depending on the processing parameters is also of interest to tailor the required material properties for different applications. It is currently being investigated for high efficiency solar cell based on CuInS2-In2S3 heterostructures, replacing CdS layers. Few studies have been reported on nanostructured In2S3 grown by several methods.

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Monaico, Ed, V. Postolache, E. Borodin, V. V. Ursaki, O. Lupan, R. Adelung, K. Nielsch, and I. M. Tiginyanu. "Control of persistent photoconductivity in nanostructured InP through morphology design." Semiconductor Science and Technology 30, no. 3 (February 11, 2015): 035014. http://dx.doi.org/10.1088/0268-1242/30/3/035014.

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Urteaga, R., O. Marín, L. N. Acquaroli, D. Comedi, J. A. Schmidt, and R. R. Koropecki. "Enhanced photoconductivity and fine response tuning in nanostructured porous silicon microcavities." Journal of Physics: Conference Series 167 (May 1, 2009): 012005. http://dx.doi.org/10.1088/1742-6596/167/1/012005.

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39

Iaseniuc, O., and M. Iovu. "Characterization of some optical and physical properties of As11.2S48.0Sb28.8Te12.0 and As20.8S48.0Sb19.2Te12.0 nanostructured polycrystalline semiconductors." Chalcogenide Letters 19, no. 2 (February 2022): 117–24. http://dx.doi.org/10.15251/cl.2022.192.117.

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This work presents the characterization of As-S-Sb-Te nanostructured polycrystalline semiconductors by X-ray fluorescence (XRF), X-ray diffraction (XRD), electron microscopy (SEM), optical as well as photoelectric methods. The XRD patterns have been shown the presence of amorphous and nanocrystalline phases with the main structural units As2S3, Sb2S3 and Sb2Те3. The IR transmission spectra show a high transparence just with a single weak absorption band about ν=2340 cm-1 caused of the presence of H2S impurity. It was also observed that for the alloys of As11.2S48.0Sb28.8Te12.0 and As20.8S48.0Sb19.2Te12.0, with an increase in the number of As atoms, the transmission in the IR region also increase. The maximum of steady-state photoconductivity for both materials, measured in the linear portion of I-V characteristics, is situated around =0.96 m.

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Mayorova, T. L., V. G. Klyuev, and A. I. Zvyagin. "Explosion Dependence of the Photoconductivity of Nanostructured CdZnS Films on the Excitation Time." Bulletin of the Russian Academy of Sciences: Physics 84, no. 7 (July 2020): 824–28. http://dx.doi.org/10.3103/s1062873820070175.

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41

Karan, Santanu, Dhrubajyoti Basak, and Biswanath Mallik. "Persistence in photoconductivity and optical property of nanostructured copper (II) phthalocyanine thin films." Current Applied Physics 10, no. 4 (July 2010): 1117–22. http://dx.doi.org/10.1016/j.cap.2010.01.011.

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Koshy, Obey, and M. Abdul Khadar. "Evolution of nanostructure, defect-free photoluminescence and enhanced photoconductivity of oxidized Zn films." Journal of Applied Physics 109, no. 12 (June 15, 2011): 124315. http://dx.doi.org/10.1063/1.3592650.

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Ibrahim, Isam M. "The effect of rear earth doping CdS nanostructure on structural, optical and photoconductivity properties." Iraqi Journal of Physics (IJP) 17, no. 40 (March 1, 2019): 108–18. http://dx.doi.org/10.30723/ijp.v17i40.411.

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Rare earth elements (Cerium, Lanthanum and Neodymium) doped CdS thin films are prepared using the chemical Spray Pyrolysis Method with temperature 200 oC. The X-ray diffraction (XRD) analysis refers that pure CdS and CdS:Ce, CdS:La and CdS:Nd thin films showed the hexagonal crystalline phase. The crystallite size determined by the Debye-Scherrer equation and the range was (35.8– 23.76 nm), and it was confirmed by field emission scanning electron microscopy (FE-SEM). The pure and doped CdS shows a direct band gap (2.57 to 2.72 eV), which was obtained by transmittance. The room-temperature photoluminescence of pure and doped CdS shows large peak at 431 nm, and two small peaks at (530 and 610 nm). The Current – voltage measurement in dark and illumination (100 mW/cm2, 183 mW/cm2 and 288 mW/cm2) condition. The photocurrent increases and the resistivity decreases with the light intensity increases. So film reveals photoconductivity phenomena suggesting it's useful for optoelectronic applications.

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Güneş, Mehmet, Jimmy Melskens, and Arno H. M. Smets. "The native and metastable defects and their joint density of states in hydrogenated amorphous silicon obtained from the improved dual beam photoconductivity method." Journal of Applied Physics 133, no. 12 (March 28, 2023): 125702. http://dx.doi.org/10.1063/5.0138257.

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In this study, undoped hydrogenated amorphous silicon (a-Si:H) thin films deposited under moderate dilution ratios of silane by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) have been investigated using steady-state photoconductivity and improved dual beam photoconductivity (DBP) methods to identify changes in multiple gap states in annealed and light-soaked states. Four different gap states were identified in annealed state named as A, B, C, and X states. The peak energy positions of these Gaussian distributions are consistent with those recently identified by Fourier transform photocurrent spectroscopy (FTPS). After in situ light soaking, their density increases with different rates as peak energy positions and half-widths remain unaffected. The electron-occupied A and B states located below the dark Fermi level and their density and ratios in the annealed and light-soaked states correlate well with those defects detected by time-domain pulsed electron paramagnetic resonance (EPR) experiments. The A, B, and X states located closer to the middle of the bandgap anneal out at room temperature in dark and define the “fast” states. However, the C states show no sign of room temperature annealing such that they must define the “slow” states in undoped a-Si:H. The results found in this study indicate that the anisotropic disordered network is a more appropriate model than previously proposed defect models based on the continuous random network to define the nanostructure of undoped a-Si:H, where multiple defects, D0 and non-D0 defects, can be identified by using the improved DBP method.

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Duraisamy, Navaneethan, Ki Rin Kwon, Jeongdai Jo, and Kyung-Hyun Choi. "Development of Nanostructured ZnO Thin Film via Electrohydrodynamic Atomization Technique and Its Photoconductivity Characteristics." Journal of Nanoscience and Nanotechnology 14, no. 8 (August 1, 2014): 5849–55. http://dx.doi.org/10.1166/jnn.2014.8877.

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46

Oekermann, T., T. Yoshida, H. Tada, and H. Minoura. "Color-sensitive photoconductivity of nanostructured ZnO/dye hybrid films prepared by one-step electrodeposition." Thin Solid Films 511-512 (July 2006): 354–57. http://dx.doi.org/10.1016/j.tsf.2005.12.032.

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Srivathsa, Manu, Pawan Kumar, and B. V. Rajendra. "Ultraviolet photoconductivity and photoluminescence properties of spray pyrolyzed ZnO nanostructure: Effect of deposition temperature." Optical Materials 131 (September 2022): 112726. http://dx.doi.org/10.1016/j.optmat.2022.112726.

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48

Ganesh, T., S. Rajesh, and Francis P. Xavier. "Sol-Gel Preparation, Deposition and Characterization of Nanostructured Aluminium Doped Zinc Oxide." Journal of Nano Research 24 (September 2013): 96–106. http://dx.doi.org/10.4028/www.scientific.net/jnanor.24.96.

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Pure and Aluminium-doped ZnO (Zn1-xAlxO) x = 0 to 5 wt% thin films were deposited onto glass substrate by sol-gel spin coating method. The influence of various aluminium concentration in ZnO thin films on the structural, surface, optical and photoconducting properties were investigated. The GIXRD studies confirmed the polycrystalline nature with wurtzite structure of pure and Al doped ZnO films. Films with 1.5 % concentration of aluminium showed maximum absorption and transmission in the UV and visible regions respectively. The FESEM images showed crack free films with increasing grain boundaries upon doping. The average grain size is found to decrease due to aluminium doping. AFM images showed doped films with 1.5 % have better smoothness than other films. The photoconductivity measurements reveal that there is increase in the photocurrent compared to dark current for the Al doped ZnO. The photocurrent reaches its maximum value for ZnO: Al-1.5 % and then decreases upon increase in Al concentration. The photoresponse has slightly degraded upon aluminium doping onto ZnO. Temperature dependent conductivity shows that the thermal activation energy for the film decreases up to 1.5 % aluminium concentration and then increases for other concentrations in the temperature range 308 to 375K.

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Zhou, W. L., J. Wiemann, K. L. Stokes, and C. J. O’Connor. "Monodisperse Pbse Nanoparticle Self-Assembling Nanoarrays Before and After Annealing." Microscopy and Microanalysis 7, S2 (August 2001): 314–15. http://dx.doi.org/10.1017/s1431927600027641.

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A variety of semiconductor and metal nanoparticles can be synthesized and tunable in size from about 10 to 200 Å using size-selective separation technique. Preparation of monodisperse samples enables systematic characterization of the structural, electron, and optical properties of materials as they evolve from molecular to bulk in the nanometer size range. Sample uniformity makes it possible to manipulate nanocrystals into close-packed, glassy and ordered nanocrystal. At inter-particle separations 5-100 Å, dipole-dipole interactions lead to energy transfer between neighboring nanocrystals, and electronic tunneling between proximal nanocrystals gives rise to dark and photoconductivity. The fabrication of monodisperse ordered nanoarrays with the inter-particle separations less than 5Å will be very important to study its physical properties since interaction between neighboring nanocrystals cause otherwise insulating assemblies to become semiconducting, metallic, or superconducting depending on nanocrystals composition. Here we present the fabrication of monodisperse PbSe nanoarrays with inter-particle distance less than 5 Å and its nanostructure study.

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Pai, Yi-Hao, and Gong-Ru Lin. "Crystalline-Phase-Dependent Photoluminescence and Photoconductivity of Roughened ZnO Nanostructure Grown by Self-Electrochemical Transformation." Journal of The Electrochemical Society 158, no. 8 (2011): E88. http://dx.doi.org/10.1149/1.3601875.

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Journal articles on the topic 'Photoconductivity - Nanostructures'

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