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Journal articles on the topic 'Cadmium-free semiconductors'
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Kozlov D. V., Zholudev M. C., Rumyantsev V. V., Ikonnikov A. V., Pavlov S., Hubers H.-W., and Morozov S. V. "Temperature dependence of the Fermi level in HgCdTe narrow-gap bulk films at different mercury vacancy concentrations." Semiconductors 56, no. 5 (2022): 313. http://dx.doi.org/10.21883/sc.2022.05.53424.9789.
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We calculate Fermi level position in bulk HgCdTe with cadmium fraction from 19 to 22% as a function of temperature for different concentrations of mercury vacancies forming double-charged acceptors with ionization energies of 11 and 21 meV for neutral and singly charged states respectively. The concentration of free carriers in the bands at different temperatures and the proportion of acceptor centres in different charge states are calculated as well. The results explain the fast temperature quenching of photoconductivity involving the vacancies states. It is also shown that in a p-type material conductivity dependence on temperature includes an exponential growth region with a characteristic energy much greater than a half of the bandgap at zero temperature expected for an intrinsic semiconductor. Keywords: narrow-gap semiconductors, HgCdTe, Fermi level, doubly charged acceptors.
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Li, Xiu-Ping, Rong-Jin Huang, Cong Chen, Tianduo Li, and Yu-Ji Gao. "Simultaneous Conduction and Valence Band Regulation of Indium-Based Quantum Dots for Efficient H2 Photogeneration." Nanomaterials 11, no. 5 (April 26, 2021): 1115. http://dx.doi.org/10.3390/nano11051115.
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Indium-based chalcogenide semiconductors have been served as the promising candidates for solar H2 evolution reaction, however, the related studies are still in its infancy and the enhancement of efficiency remains a grand challenge. Here, we report that the photocatalytic H2 evolution activity of quantized indium chalcogenide semiconductors could be dramatically aroused by the co-decoration of transition metal Zn and Cu. Different from the traditional metal ion doping strategies which only focus on narrowing bandgap for robust visible light harvesting, the conduction and valence band are coordinately regulated to realize the bandgap narrowing and the raising of thermodynamic driving force for proton reduction, simultaneously. Therefore, the as-prepared noble metal-free Cu0.4-ZnIn2S4 quantum dots (QDs) exhibits extraordinary activity for photocatalytic H2 evolution. Under optimal conditions, the Cu0.4-ZnIn2S4 QDs could produce H2 with the rate of 144.4 μmol h−1 mg−1, 480-fold and 6-fold higher than that of pristine In2S3 QDs and Cu-doped In2S3 QDs counterparts respectively, which is even comparable with the state-of-the-art cadmium chalcogenides QDs.
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Shrestha, S., and C. K. Sarkar. "Comparative studies on the electronic transport in magnetically quantized low band gap semiconductor system." BIBECHANA 17 (January 1, 2020): 34–41. http://dx.doi.org/10.3126/bibechana.v17i0.21741.
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The Q1D system formed by magnetically confined system is attracting attention of researchers in device application because it is capable of over-looking the various techniques of fabrication difficulties and defects created by such fabrication techniques. In the presence of a high magnetic field, the transverse component of the energy dispersion relation gets quantized into various equally spaced energy levels called Landau levels and the motion of the carriers is completely restricted. However, the longitudinal component along the field is still free to move. The mobility of such system is enhanced when a low effective mass semiconductors n-HgCdTe (Mercury Cadmium Telluride) is used. The band structure of n-HgCdTe is found to be nonparabolic due to its low band gap according to Kane [Phadke and Sharma, 1975]. Recent publications, based on experimental verifications of transport coefficient of n-HgCdTe of Chen and Sher [Chen and Sher, 1982] show that the band structure of Mercury Cadmium Telluride (MCT) is more hyperbolic in nature rather than nonparabolic. The author has compared the effect of band structures on the various transport properties of MCT such as mobility, Seebeck coefficient, thermal conductivity, figure of merit (Z) etc. The figure of merit is a very important property of a material to be used in thermoelectric devices, such as cooler, refrigerator etc. The product of Z and temperature i.e. (ZT), a dimensionless quantity is found to be maximum for parabolic band structure and is followed by nonparabolic and hyperbolic band structures for all ranges of variation of temperature as well as magnetic field. Taking the hyperbolic band structure of MCT, the effect of high and low temperature scattering mechanisms on ZT is also observed.
BIBECHANA 17 (2020) 34-41
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Yu, Yuan-Fang, Ye Zhang, Fan Zhong, Lin Bai, Hui Liu, Jun-Peng Lu, and Zhen-Hua Ni. "Highly Sensitive Mid-Infrared Photodetector Enabled by Plasmonic Hot Carriers in the First Atmospheric Window." Chinese Physics Letters 39, no. 5 (May 1, 2022): 058501. http://dx.doi.org/10.1088/0256-307x/39/5/058501.
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The first atmospheric window of 3–5 μm in the mid-infrared (MIR) spectral range pertains to crucial application fields, with particular scientific and technological importance. However, conventional narrow-bandgap semiconductors operating at this band, represented by mercury cadmium telluride and indium antimonide, suffer from limited specific detectivity at room temperature and hindered optoelectronic integration. In this study, a plasmonic hot electron-empowered MIR photodetector based on Al-doped ZnO (AZO)/bi-layer graphene heterostructure is demonstrated. Free electrons oscillate coherently in AZO disk arrays, resulting in strong localized surface plasmon resonance (LSPR) in the MIR region. The photoelectric conversion efficiency at 3–5 μm is significantly improved due to plasmon-induced hot-electron extraction and LSPR-enhanced light absorption. The specific detectivity reaches about 1.4 × 1011 Jones and responsivity is up to 4712.3 A/W at wavelength of 3 μm at room temperature. The device’s specific detectivity is among the highest performance of commercial state-of-the-art photodetectors and superior to most of the other 2D materials based photodetectors in the MIR region. These results demonstrate that a plasmonic heavily doped metal oxides/2D material heterostructure is a suitable architecture for constructing highly sensitive room-temperature MIR photodetectors.
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RAO, M. C. "SCIENTIFIC APPROACH TO RENEWABLE ENERGY THROUGH SOLAR CELLS." International Journal of Modern Physics: Conference Series 22 (January 2013): 11–17. http://dx.doi.org/10.1142/s2010194513009860.
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Renewable energy is increasingly viewed as critically important globally. Solar cells convert the energy of the sun into electricity. The method of converting solar energy to electricity is pollution free, and appears a good practical solution to the global energy problems. Energy policies have pushed for different technologies to decrease pollutant emissions and reduce global climate change. Photovoltaic technology, which utilizes sunlight to generate energy, is an attractive alternate energy source because it is renewable, harmless and domestically secure. Transparent conducting metal oxides, being n-type were used extensively in the production of heterojunction cells using p-type Cu 2 O . The long held consensus is that the best approach to improve cell efficiency in Cu 2 O -based photovoltaic devices is to achieve both p- and n-type Cu 2 O and thus p-n homojunction of Cu 2 O solar cells. Silicon, which, next to oxygen, is the most represented element in the earth's crust, is used for the production of monocrystalline silicon solar cells. Silicon is easily obtained and processed and it is not toxic and does not form compounds that would be environmentally harmful. In contemporary electronic industry silicon is the main semiconducting element. Thin-film cadmium telluride (CdTe) solar cells are the basis of a significant technology with major commercial impact on solar energy production. Polycrystalline thin-film solar cells such as CuInSe 2 (CIS), Cu (In, Ga) Se 2 (CIGS) and CdTe compound semiconductors are important for terrestrial applications because of their high efficiency, long-term stable performance and potential for low-cost production. Highest record efficiencies of 19.2% for CIGS and 16.5% for CdTe have been achieved.
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Yang, Wentao, Xiaoqun Gong, and Jin Chang. "Development of Novel Cadmium-Free AgInS2 Semiconductor Nanoparticles." Journal of Nanoscience and Nanotechnology 16, no. 3 (March 1, 2016): 2172–83. http://dx.doi.org/10.1166/jnn.2016.10946.
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Deglmann, Peter, Reinhart Ahlrichs, and Kakha Tsereteli. "Theoretical studies of ligand-free cadmium selenide and related semiconductor clusters." Journal of Chemical Physics 116, no. 4 (January 22, 2002): 1585–97. http://dx.doi.org/10.1063/1.1427718.
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Asano, Hiroshi, and Takahisa Omata. "Design of cadmium-free colloidal II–VI semiconductor quantum dots exhibiting RGB emission." AIP Advances 7, no. 4 (April 2017): 045309. http://dx.doi.org/10.1063/1.4982256.
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Uematsu, Taro, Kazutaka Wajima, Watcharaporn Hoisang, Dharmendar Kumar Sharma, Shuzo Hirata, Takahisa Yamamoto, Tatsuya Kameyama, Martin Vacha, Tsukasa Torimoto, and Susumu Kuwabata. "Narrow-Band Photoluminescence from Cadmium-Free I-III-VI Ternary Semiconductor Quantum Dots By Surface Modification." ECS Meeting Abstracts MA2020-02, no. 42 (November 23, 2020): 2727. http://dx.doi.org/10.1149/ma2020-02422727mtgabs.
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Smentkowski, Vincent S., Sara G. Ostrowski, Lauraine Denault, and Charles G. Woychik. "Characterization of Surface and Sub- Surface Defects on Devices using Complimentary Techniques." Microscopy Today 16, no. 6 (November 2008): 18–20. http://dx.doi.org/10.1017/s1551929500062325.
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Being able to differentiate surface from bulk defects on devices requires the use of complimentary characterization tools. In this article, we show how light microscopy, scanning electron microscopy, energy dispersive X-ray analysis, and time of flight secondary ion mass spectrometry provides complimentary information about the surface and sub-surface composition, topography, and microstructure of a semiconductor device.To create a gamma-ray spectroscopy detector, electrical contacts consisting of a blanket coated cathode and a pixilated anode can be deposited directly on opposite faces of a cadmium zinc telluride (CZT) crystal. The contact metallization must adhere to the surfaces, and the streets between adjacent anode pads must be free of residual metal and contaminants to avoid excessive interpixel leakage currents. The analysis reported below was used to validate the structure and composition of the contact metal stack and to characterize the streets of the anode pad array.
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Fasquelle, Didier, Stéphanie Députier, Valérie Bouquet, and Maryline Guilloux-Viry. "Effect of the Microstructure of ZnO Thin Films Prepared by PLD on Their Performance as Toxic Gas Sensors." Chemosensors 10, no. 7 (July 16, 2022): 285. http://dx.doi.org/10.3390/chemosensors10070285.
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In 2008, the modified European Restriction of Hazardous Substances (RoHS) directive prohibited the use of hazardous substances such as lead, cadmium, and mercury. As such, an urgent need for lead-free components emerged in Europe. In this frame, we have decided to study the microstructure influence of zinc oxide thin films on the detection of hydrogen sulfide (H2S). Zinc oxide thin films were deposited by PLD on silicon substrates under different conditions to modify the microstructure. In order to compare our demonstrators to current commercial semiconductor gas sensors, measurements under H2S were also performed with sensors from Figaro and Winsen corporations. Gas sensors were therefore implemented by using commercial cases in view to test them with Simtronics gas detector DG477. The good sensitivity values measured at T = 400 °C under 100 ppm H2S, and response times as low as 30 s, definitely confirm that ZnO thin films could be developed for commercial sensors.
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Laxman, Karthik, Tanujjal Bora, Salim H. Al-Harthi, and Joydeep Dutta. "Improved Sensitization of Zinc Oxide Nanorods by Cadmium Telluride Quantum Dots through Charge Induced Hydrophilic Surface Generation." Journal of Nanomaterials 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/919163.
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This paper reports on UV-mediated enhancement in the sensitization of semiconductor quantum dots (QDs) on zinc oxide (ZnO) nanorods, improving the charge transfer efficiency across the QD-ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies) in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe) QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect-free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD-ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.
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Ahmed, Nisar, Azeem Nabi, Jawad Nisar, Muhammad Tariq, Muhammad Arshad Javid, and M. H. Nasim. "First principle calculations of electronic and magnetic properties of Mn-doped CdS (zinc blende): a theoretical study." Materials Science-Poland 35, no. 3 (October 20, 2017): 479–85. http://dx.doi.org/10.1515/msp-2017-0084.
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AbstractThe electronic structure and magnetic properties of Mn doped zinc blende cadmium sulfide Cd1-xMnxS (x = 6.25 %) have been studied using spin-polarized density functional theory within the framework of Generalized Gradient Approximation (GGA), its further corrections including Hubbard U interactions (GGA + U) and a model for exchange and correlation potential Tran Blaha modified Becke-Johnson (TB-mBJ). Ferromagnetic interactions have been observed between Mn atoms via S atom due to strong p-d hybridization. The magnetic moments on Mn and its neighboring atoms have also been studied in detail using different charge analysis techniques. It has been observed that p-d hybridization reduced the value of local magnetic moment of Mn in comparison to its free space charge value and produced small local magnetic moments on the nonmagnetic S and Cd host sites. The magnetocrystalline anisotropy in [1 0 0] and [1 1 1] directions as well as exchange splitting parameters Noα and Noβ have been analyzed to confirm that ferromagnetism exists. We conclude that the ferromagnetic phase in Mn-doped CdS is not stable in “near” configuration but it is stable for “far” configuration. Mn doped CdS is a p-type semiconductor and the d-states at the top of the valence band edge give a very useful material for photoluminescence and magneto-optical devices.
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Shalabayev, Zhandos, Matej Baláž, Natalya Khan, Yelmira Nurlan, Adrian Augustyniak, Nina Daneu, Batukhan Tatykayev, et al. "Sustainable Synthesis of Cadmium Sulfide, with Applicability in Photocatalysis, Hydrogen Production, and as an Antibacterial Agent, Using Two Mechanochemical Protocols." Nanomaterials 12, no. 8 (April 7, 2022): 1250. http://dx.doi.org/10.3390/nano12081250.
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CdS nanoparticles were successfully synthesized using cadmium acetate and sodium sulfide as Cd and S precursors, respectively. The effect of using sodium thiosulfate as an additional sulfur precursor was also investigated (combined milling). The samples were characterized by XRD, Raman spectroscopy, XPS, UV-Vis spectroscopy, PL spectroscopy, DLS, and TEM. Photocatalytic activities of both CdS samples were compared. The photocatalytic activity of CdS, which is produced by combined milling, was superior to that of CdS, and was obtained by an acetate route in the degradation of Orange II under visible light irradiation. Better results for CdS prepared using a combined approach were also evidenced in photocatalytic experiments on hydrogen generation. The antibacterial potential of mechanochemically prepared CdS nanocrystals was also tested on reference strains of E. coli and S. aureus. Susceptibility tests included a 24-h toxicity test, a disk diffusion assay, and respiration monitoring. Bacterial growth was not completely inhibited by the presence of neither nanomaterial in the growth environment. However, the experiments have confirmed that the nanoparticles have some capability to inhibit bacterial growth during the logarithmic growth phase, with a more substantial effect coming from CdS nanoparticles prepared in the absence of sodium thiosulfate. The present research demonstrated the solvent-free, facile, and sustainable character of mechanochemical synthesis to produce semiconductor nanocrystals with multidisciplinary application.
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Salawu, M. A., A. B. Alabi, J. T. Adeleke, H. T. Sulu, S. B. Sharafa, and T. Akomolafe. "Effects of Temperature on Morphological, Structural and Optical Characteristics of CdTe Films for PV Applications." Nigerian Journal of Basic and Applied Sciences 27, no. 1 (May 26, 2020): 10–16. http://dx.doi.org/10.4314/njbas.v27i1.2.
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Cadmium telluride (CdTe) is a direct band gap semiconductor for direct light-to-electricity conversion. The films are promising photovoltaic materials for CdS/CdTe solar cells because of its energy band gap of 1.5 eV and higher absorption co-efficient (>104cm-1). This work presents the characterization of 1 μm CdTe films for photovoltaic applications. The films were deposited on cleaned glass substrates using thermal evaporation. The effect of annealing temperatures (as deposited, 400°C and 500°C) on morphological, structural and optical characteristics of CdTe films was investigated for an hour and characterized with Scanning Electron Microscope (SEM), Powder X-ray diffraction (PXRD) and UV-Visible spectrophotometer. The results revealed that the reflectance characteristics of CdTe films depend on the wavelength of electromagnetic spectra. The maximum percentage optical transmittance of CdTe films for as-grown, 400°C and 500oC films were 59%, 60% and 58% respectively at 800 nm wavelength. The absorbance decreases with increasing in wavelength and was found to be 1.65, 1.25 and 0.85 % for the as-grown, 400°C and 500oC films respectively. The absorption coefficient exhibits higher values in the shorter wavelength and decreases as the wavelength and temperatures increases and the band gap becomes wider. The SEM analyses showed that the films were homogenous and free from crystal defects. The results revealed that 1 μm CdTe film may be used as absorber layer in CdS/CdTe thin film solar cells.
Keywords: CdTe, Glass substrate, Thermal evaporation, Annealing temperature, Energy band gap
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Fatemi, Ali, and Milad Rasouli. "(Digital Presentation) Engineering Band Gap of Chalcogenide Nanomaterial-Polymer Composites." ECS Meeting Abstracts MA2022-01, no. 32 (July 7, 2022): 2492. http://dx.doi.org/10.1149/ma2022-01322492mtgabs.
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Over the last two decades, engineering the optical properties of nanoscale structures (nanowires, quantum dots, and nanotubes), i.e., band gap, absorption, and photoluminescence radiation, which can be manipulated in sulfide-based semiconductor materials, has received a lot of attention. Due to their tunable characteristics, these materials were introduced for potential applications ranging from medicine and communications to energy and various sensors (1). In addition, chemical synthesis methods provide the desired structure, material, reproducibility, and possibility of large-scale production, along with sustainable industrialization and foster innovation of these material systems. Polyvinyl-alcohol (PVA) is one of the functional polymers, in addition to the ability to stabilize the nanomaterial solution, which can change the optical properties of the material (2). Currently, the majority of sulfide-based nanomaterials are cadmium, lead, and silver, which have shown a wide range of applications. Here, PVA/CdS, PVA/PbS, and PVA/Ag2S nanocomposites were investigated as the desired composites. For optical studies, band gap, absorption, and photoluminescence irradiation of these material systems were performed. The structural and morphological properties were examined by scanning electron microscopy, DLS, and X-ray diffraction. The band gap value of synthesized nanoparticles in the polymer bed was 3.48, 3.08, and 2.27 eV for PVA/CdS, PVA/PbS, and PVA/Ag2S, respectively, whereas for pure PVA the band gap value was 4.75 eV. As shown in Figure 1, with the entry of nanoparticles into the polymer, a shift in the composite band gap can be seen that corresponds to an increase in absorption. Photoluminescence irradiations for polymer-nanoparticle composites showed that silver-polymer nanoparticles have intense irradiance at 405nm, while cadmium-polymer and lead-polymer composites have intense irradiance at 430nm and 500nm, respectively. An X-ray diffraction pattern was indicated for each of the crystals, confirming the presence of the expected crystal structure. The DLS of materials represents sizes of 150, 125, and 175 nm for PVA/CdS, PVA/PbS, and PVA/Ag2S. Besides, the structure of the material systems was examined by FE-SEM microscopy, which showed a homogeneous distribution of particles in the polymer and a cubic nanoparticle structure for PVA/PbS and a spherical for PVA/Ag2S and PVA/CdS. Our findings show that polymer-nanomaterial composites are potential candidates for use in sensors and solar energy cells, especially non-toxic Ag2S nanomaterials (3) that have already been documented as an emerging platform for in-vivo imaging. References: Khan H, Dwivedi PK, Husain M, Zulfequar M. Tunable optical bandgap in PVA/Ge10As40Se50 chalcogenide glass (ChG) nanocomposites free standing films. Optik. 2021;245:167677. Badawi A, Althobaiti M, Alharthi SS. Exploring the structural, optical and photoluminescence properties of tin-doped manganese sulfide nanoparticles encapsulated with PVA for potential application in optoelectronics. Physica E: Low-dimensional Systems and Nanostructures. 2022;140:115190. Nieves LM, Mossburg K, Hsu JC, Maidment AD, Cormode DP. Silver chalcogenide nanoparticles: a review of their biomedical applications. Nanoscale. 2021. Figure 1
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Deen, M. Jamal. "(Digital Presentation) Biosensors – Researching at the Crossroads of Engineering and the Sciences." ECS Meeting Abstracts MA2022-01, no. 18 (July 7, 2022): 1033. http://dx.doi.org/10.1149/ma2022-01181033mtgabs.
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It has been a pleasure and honor to know Dr. Landheer for more than three decades and to have collaborated with him. In this invited presentation, I will focus on one aspect of our collaboration – the topic of Biosensors – which was our last research collaboration. In the list of references [1-15], I provide all publications we collaborated on since 1986. Biosensors are increasingly used in environmental applications, especially for water quality monitoring. This is because the availability of safe drinking water is fundamental to our good health. However, as water resources get increasingly stressed, ensuring a safe water supply and effective water treatment becomes increasingly important. In addition, waterborne illnesses are a significant public health problem. At the same time, current monitoring of microbiological contamination of water currently is time-consuming, laboratory based, and frequently compromises the timeliness of health advisory warnings even when contamination is found. Therefore, rapid detection of unsafe water can contribute greatly to mitigating the morbidity and mortality associated with waterborne diseases due to microbiological contaminants. Fortunately, the research community has shown increasing interest in the development of microtechnology-based sensors for the detection and identification of the bio-contaminants. These sensing systems use the same fabrication technology that has enabled the drastic lowering of cost, exponential increase in complexity of electronic chips and widespread availability of computing resources. In this presentation, we will discuss a low-cost, electrical, label-free microfabricated biosensor that we have been developing for pathogen detection related to water quality and also for ubiquitous-healthcare applications. The use of nano-dimensions devices to create futuristic nano-biosensors for both environmental and health applications will be introduced. And we will also describe our ongoing work to create highly integrated and parallel detection systems by integrating the sensor, the processing electronics and the pre-processing stages on the same cheap substrate. Finally, the success of such a low-cost, highly integrated sensing system demands a convergence of expertise from various engineering disciplines, the physical and life sciences as well as public health. References D Landheer et al, “Bioaffinity Sensors Based on MOS Field—Effect Transistors,” in Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications, Eds. Ren, Pearton, Taylor & Francis Books, Boca Raton, 215-265, 2010. MW Shinwari, et al, Microfabricated Reference Electrodes and their Biosensing Applications, Sensors, Vol. 10(3), pp. 1679-1715, 2010. MW Shinwari, MJ Deen, D Landheer, “Study of the Electrolyte-Insulator-Semiconductor Field-Effect Transistor with Applications in Biosensor Design,” Microelectronics Reliability, Vol. 47(12), pp. 2025-2057, 2007. D Landheer, et al, Calculation of the Response of Field-Effect Transistors to Charged Biological Molecules, IEEE Sensors Journal, Vol. 7, 1233-1242, 2007. WH Jiang, et al, Post-processing of Commercial CMOS Chips for the Fabrication of DNA Bio-FET Sensor Arrays, Proceedings of MRS Symposium - Fall Meeting, 6 pages, 2006. Bioelectronics, Biointerfaces, and Biomedical Applications 2, Eds., D Landheer, R. Bashir, M. Deen, C. Kranz, C. Liu, M. Madou, A. Offenhaeusser, R. Schasfoort, ECS Transactions, Vol. 3, Issue 26, 2006. MJ Deen, et al, Noise Considerations in Field-Effect Biosensors, Journal Applied Physics, Vol. 100, #074703, 8 pages, 2006. MJ Deen, et al, High Sensitivity Detection of Biological Species via the Field-Effect, Proceedings of the IEEE ICCDCS, Playa del Carmen, Mexico, pp. 381-385, 2006. D Landheer, et al, Model for the Field-Effect from Layers of Biological Macromolecules on the Gates of Metal-Oxide-Semiconductor Transistors, Journal Applied Physics, Vol. 98, # 044701, 2005. Silicon Nitride and Silicon Dioxide Thin Insulating Films, Eds., R.E. Sah, MJ Deen, D Landheer, K.B. Sundaram, W.D. Brown, D. Misra, ECS Proceedings PV-03, 636 pages 2003. Silicon Nitride and Silicon Dioxide Thin Insulating Films, Eds., K.B. Sundaram, MJ Deen, D Landheer, W.D. Brown, D. Misra, M.D. Allendorf, R.E. Sah, ECS Proceedings Volume PV 2001-7, 2001. MJ Deen, et al, Low Frequency Noise in Cadmium Selenide Thin-Film Transistors, Applied Physics Letters, Vol. 77(14), pp. 2234-2236, 2000. MJ Deen, et al, Low Frequency Noise in CdSe Thin-Film Transistors, ESSDERC 2000, Cork, Ireland, pp. 592-595, 2000. MJ Deen, et al, NbN Thin Films Reactively Sputtered with a High Field DC Magnetron, Journal of Vacuum Science and Technology A, Vol. 6(4), pp. 2299-2303, 1988. MJ Deen, et al, The Effect of the Deposition Rate on the Properties of DC Magnetron Sputtered NbN Thin Films, Bull Am Phys Soc., Vol. 32(3), p. 646, 1987.
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Rivera-Vázquez, Daniel, Yohaselly Santiago-Rodríguez, Miguel A. González, and Miguel E. Castro-Rosario. "Quantum Confinement Effects in Calcium Sulfide: The Role of Indirect Transitions in the Red Shift of the Band Edge in Semiconductor Nanoparticles." MRS Proceedings 1694 (2014). http://dx.doi.org/10.1557/opl.2014.891.
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ABSTRACTCalcium sulfide (CaS) nanoparticles are cadmium free fluorescent nanostructures with potential applications in nanomedicine and photovoltaic cells. We report on the synthesis and optical properties of CaS nanoparticles prepared by the reaction of Ca(CH3CO2)2 and DMSO in a microwave. The absorption spectra of CaS prepared from this method consists of a well-defined peak in the UV and a long wavelength tail that extends above 700 nm. Emission bands centered at around 500 nm with a long wavelength tail that extends above 600 nm are observed upon excitation at 405 nm. STM measurements reveal the formation of CaS nanoparticles with an average diameter of (3.2 ± 0.7) nm. The direct and indirect band gaps are estimated to be (0.403 ± 0.003) eV and (4.135 ± 0.006) eV, respectively. Theoretical calculations on small CaS clusters are used to establish the physical properties of calcium sulfide nanoclusters, including the optical absorption spectra. Unique to CaS nanostructures is the absorption of light at wavelengths longer that in the bulk material instead of the blue shift associated with quantum confinement effects in semiconductors. Indeed, the strong absorption bands in the visible region of the spectra of the CaS nanostructures do not have a counterpart in the gas or solid phases. The optical absorption spectra are proposed to have a significant contribution from indirect transitions which are discussed in terms of the dispersion of the phonon frequency.
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Borchert, Holger, Dorothea Scheunemann, Katja Frevert, Florian Witt, Andreas Klein, and Jürgen Parisi. "Schottky Solar Cells with CuInS2 Nanocrystals as Absorber Material." Zeitschrift für Physikalische Chemie 229, no. 1-2 (January 28, 2015). http://dx.doi.org/10.1515/zpch-2014-0595.
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AbstractColloidal semiconductor nanocrystals with tunable optical properties are promising materials for light harvesting in solar cells. So far, in particular cadmium and lead chalcogenide nanocrystals were intensively studied in this respect, and the device performance has made rapid progress in recent years. In contrast, less research efforts were undertaken to develop solar cells based on Cd- and Pb-free nanoparticles as absorber material. In the present work, we report on Schottky solar cells with the absorber layer made of colloidal copper indium disulfide nanocrystals. Absorber films with up to ∼ 500 nm thickness were realized by a solution-based layer-by-layer deposition technique. The device performance was systematically studied dependent on the absorber layer thickness. Decreasing photocurrent densities with increasing thickness revealed charge transport to be a limiting factor for the device performance.
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Faremi, A. A., S. S. Oluyamo, K. D. Adedayo, Y. A. Odusote, and O. I. Olusola. "Influence of Silicon Nanoparticle on the Electrical Properties of Heterostructured CdTe/CdS thin films based Photovoltaic Device." Journal of the Nigerian Society of Physical Sciences, August 29, 2021, 256–61. http://dx.doi.org/10.46481/jnsps.2021.267.
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This paper presents the influence of silicon nanoparticles at the interface of heterostructured Cadmium telluride and cadmium sulfide thin films based photovoltaic device with improved electrical parameters leading to tremendous improvement in CdS/CdTe thin f ilm based solar cells performance. The films of CdTe, CdS and Si were electrodeposited using electrodeposition technique to form a heterostructured CdTe/Si/CdS/FTO. The films respective structural properties were also examined using X-ray Diffractometer (XRD) before forming a heterostructured material. The heterostructured CdTe/Si/CdS/FTO and the structure without the inclusion of silicon nanoparticle were examined using electrometer for the extraction of electrical parameters such open circuit voltage (VOC), short circuit current density (JSC), and fill factor (FF). Although a large body of experimental results are available to date on the optoelectronics properties of the materials. However, there is relatively low research studies or works on the electrical properties of the materials. Therefore, we formed heterostructured based photovoltaic device and characterized the structure to determine useful electrical properties. The value obtained for VOC, JSC and FF are 418 mV, 25 mA/cm2 and 0.72 which are indicative of pin holes free semiconductor materials and no leakage path emerging from high-grade materials used in the deposition of heterostructured CdTe/Si/CdS.
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Ebhota, Williams S., and Pavel Y. Tabakov. "Assessment and performance analysis of roof-mounted crystalline stand-alone photovoltaic (SAPV) system at selected sites in South Africa." Bulletin of the National Research Centre 46, no. 1 (August 27, 2022). http://dx.doi.org/10.1186/s42269-022-00929-3.
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Abstract Background Technology is deployed to take the advantage of the ultimate energy from the sun (solar energy) to be used as heat or clean electricity. This energy is classified as “sustainable energy” or “renewable energy” because it requires a short period to naturally replenish the used energy. The application of solar energy involves the conversion of the natural energy resource into a usable form, either as heat or as electricity. The device consists of solar cells made from semiconductor materials, such as silicon, cadmium telluride, gallium arsenide, and so on. Solar potential is both location- and climate-dependent; it is characterised by low energy intensity and intermittency, which limit its application; an improvement in photovoltaic (PV) system performance will facilitate more deployment of the clean electricity system. Therefore, this study provides PV potential and system information required for reliable and optimised solar PV systems at chosen locations. This work uses a 5-stage solar PV system assessment and system performance evaluation utilising Solargis Prospect software. The PV potential and system performance of nine selected site locations in South Africa was conducted using this method. The nine PV site locations are Bloemfontein (Free State), Germiston (Gauteng), Mahikeng (North-West), Mbombela (Mpumalanga), Musgrave (Kwazulu-Natal), Musina (Limpopo), Port Nolloth (Northern Cape), Port Elizabeth (Eastern Cape), and Worcester (Western Cape). Result The results of the study were categorised into PV meteorological and system performance parameters as follows. Photovoltaic meteorological parameters—the site in Mahikeng has the highest global horizontal irradiance (GHI), 2156 kWh/m2, and a corresponding specific PV power output (1819.3 kWh/kWp), closely followed by Bloemfontein (2111.5 kWh/m2, 1819.4 kWh/kWp) and Port Nolloth (2003.2 kWh/m2, 1820.5 kWh/kWp). The lowest GHI (1645.1 kWh/m2) and specific PV power output (1436.6 kWh/kWp) were recorded in Musgrave. Photovoltaic system performance parameters—the range of performance ratio (PR) between 75.8 and 77.7% was reported across the nine sites. This ratio met the acceptable benchmark of PR. The highest specific PV power output loss, 118.8 kWh/kWp, was obtained at sites in Bloemfontein, Mahikeng, and Port Nolloth, while the lowest, 93.8 kWh/kWp, was in Musgrave. Conclusions The results of the solar PV potential assessment and the evaluation of PV systems performance in the chosen sites across the nine provinces of South Africa show huge PV potential and energy yield. From the results, it was observed that the range of the yearly average of: (1) GHI among the sites is 1645.1–2156 kWh/m2; (2) direct normal irradiation among the sites is 1785.3–2559.3 kWh/m2; (3) diffuse horizontal irradiation among the sites is 512.5–686kWh/m2; (4) global tilted irradiation among the sites is 1849.2–2397.1 kWh/m2; (5) the temperature (TEMP) among the sites is 16–23 °C; (6) specific PV power output (PVOUT specific) among the sites is 1436.6–1820.5 kWh/kWp; (7) total PV power output (PVOUT total) among the sites is 14.366–2397.1 MWh; and (8) the performance ratio among the sites is 75.8–77.7%. Based on the solar resource and performance results of the PV system obtained, the deployment of monocrystalline solar PV technology in all the considered sites across South Africa is technically viable.