Добірка наукової літератури з теми "Semiconducting Hybrid Structures"

Semiconducting materials are important photonic materials and the technologies developed have been utilized in many fields of the modern society and they are closely related to the quality of our life. The main applications of the materials are for light source and sensing originated from interaction of photons and matters. In this invited talk, I will first present our work on the properties of the semiconducting materials and their applications as lasers and photodetectors, and then present integrated hybrid subwavelength structures which show significant enhancement on device performance. It is believed that complex hybrid structures which combine quantum-and hetero-structures made of semiconducting materials, and subwavelength structure for performance enhancement are the main focus in the near future.

In this study, stretchable organic–inorganic hybrid thin-film transistors (TFTs) are fabricated on a polyimide (PI) stiff-island/elastomer substrate using blends of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and poly(methyl methacrylate) (PMMA) and oxide semiconductor In-Ga-Zn-O as the gate dielectric and semiconducting layer, respectively. Carrier mobility, Ion/Ioff ratio, and subthreshold swing (SS) values of 6.1 cm2 V−1 s−1, 107, and 0.2 V/decade, respectively, were achieved. For the hybrid TFTs, the endurable maximum strain without degradation of electrical properties was approximately 49%. These results correspond to those obtained in the first study on fabrication of stretchable hybrid-type TFTs on elastomer substrate using an organic gate insulator and oxide semiconducting active channel structure, thus indicating the feasibility of a promising device for stretchable electronic systems.

Interfaces formed at metal/semiconductor hybrid system have the peculiar electronic characteristics depending on the thickness of metal layer. The different characteristics tune light responses of the metallic and semiconducting layers, resulting in various photocatalytic hydrogen evolution activities in the hybrid system.

CoNi and Pt–CoNi magnetic layers on indium-tin oxide (ITO) substrates modified by an alkanethiol self-assembled monolayer (SAM) have been electrochemically obtained as an initial stage to prepare semiconducting layer-SAM-magnetic layer hybrid structures.

We report nanophotonic silicon-based devices for hybrid integration: 1D photonic crystal (PhC) on optical fiber, i. e. fiber Bragg grating (FBG) sensing probe integrated in fiber laser structure for chemical sensors and slotted planar 2D PhC cavity combined with carbon nanotube (CNT) towards light nanosources. The experiments have been carried out by integrating 1D PhC on optical fiber in fiber laser structure. This structure possesses many advantages including high resolution for wavelength shift, high optical signal-to-noise ratio (OSNR) of about 50~dB, the small full width at half-maximum (FWHM) of about 0.014~nm therefore its accuracy is enhanced, as well as the precision and capability are achieved for remote sensing. Low nitrate concentration in water from 0 to 80 ppm has been used to demonstrate its sensing ability in the experiment. The proposed sensor can work with good repeatability, rapid response, and its sensitivity can be obtained of \(3.2\times 10^{ - 3}\) nm/ppm with the limit of detection (LOD) of 3~ppm. For 2D PhC cavity, enhancement of photoluminescence of CNT emission is observed. The semiconducting single-walled carbon nanotubes (s-SWNTs) solution was prepared by polymer-sorted method and coupled with the confined modes in silicon slotted PhC cavities. The enhancement ratio of 1.15 is obtained by comparing between the PL peaks at two confined modes of the cavity. The PL enhancement result of the integrated system shows the potential for the realization of on-chip nanoscale sources.

We performed first-principles calculation to show that a host–guest silicon nanostructure can exhibit half-metallic properties, wherein the host is a single-walled hexagonal silicon nanotube while the guest is a hybrid atomic chain of Mn and Co (encapsulated in the host nanotube). The calculated electronic band structures indicate that the Fermi level intersects only in the spin-up band, whereas the spin-down band exhibits semiconducting characteristics.

Hybrid structures often possess superior properties to those of their component materials. This arises from changes in the structural or physical properties of the new materials. Here, we investigate the structural, electronic, and gas-adsorption properties of hybrid structures made from graphene/hexagonal boron nitride and 2H-molybdenum disulfide (G/BN@MoS2) monolayers. We consider hybrid systems in which the G/BN patch is at the Mo plane (model I) and the S plane (model II). We find that the implanted hexagon of G or BN in MoS2 alters its electronic properties: G@MoS2 (I,II) are metallic, while BN@MoS2 (I) is an n-type conducting and BN@MoS2 (II) is semiconducting. We study the molecular adsorption of some diatomic gases (H2, OH, N2, NO, CO), triatomic gases (CO2, NO2, H2S, SO2), and polyatomic gases (COOH, CH4, and NH3) on our hybrid structures while considering multiple initial adsorption sites. Our results suggest that the hybrid systems may be suitable materials for some applications: G@MOS2 (I) for oxygen reduction reactions, BN@MoS2 (I,II) for NH3-based hydrogen production, and G@MoS2 (I) and BN@MoS2 (I,II) for filtration of No, Co, SO2, H2S, and NO2.

Hybrid semiconducting silver-tetracyanoquinodimethane (AgTCNQ) nanowires decorated with Ag nanoparticles have been synthesized at room temperature in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. Hydroquinone was applied to reduce Ag+ and TCNQ to silver nanoparticles, and TCNQ–, respectively, under ambient conditions. AgTCNQ nanowires were formed via spontaneous electrolysis between Ag metal nanoparticles and TCNQ, and reaction between Ag+ and TCNQ–. Microscopic, spectroscopic, and X-ray characterizations all confirmed the formation of crystalline Ag nanoparticle–AgTCNQ nanowire hybrid structures. The ionic liquid was used as a reaction medium, but also as a stabilizing (or blocking) agent to control the nucleation and growth rate of AgTCNQ wires.

W ostatnich dwóch dekadach, w związku ze wzmożoną aktywność terrorystyczną, wzrosło zainteresowanie badaniami czujników bojowych środków trujących, w szczególności sarinu. Ze względu na wysoką toksyczność sarinu, w praktyce laboratoryjnej stosowany jest związek o podobnej budowie chemicznej - dymetylo metylofosfonian (DMMP). Większość prac dotyczących wykrywania DMMP skupia się na poszukiwaniu materiałów czułych na ten związek chemiczny i ich modyfikacji w celu uzyskania jak najlepszych parametrów czujnika. Odpowiednie zaprojektowanie urządzenia o wysokiej czułości i selektywności, a jednocześnie o niskich kosztach produkcji i eksploatacji, wymaga dogłębnej znajomości mechanizmów oddziaływania wykrywanego gazu z materiałem czułym chemicznie. W przypadku DMMP, mechanizmy te zostały zbadane dla powszechnie stosowanych w czujnikach gazów półprzewodzących tlenków metali. Wadami tych materiałów są brak selektywności i wysokie temperatury pracy. Z uwagi na to, testowane są również materiały organiczne o niskich temperaturach pracy i wyższej selektywności. Jedną z szeroko stosowanych w elektronice, w tym w czujnikach gazów, grup półprzewodników organicznych są ftalocyjaniny. Kilka prac sygnalizowało czułość ftalocyjanin względem DMMP, jednak mechanizm sensorowy nie został wyczerpująco opisany. Celem tej pracy było opracowanie metodologii badania mechanizmów sensorowych i zastosowanie jej do opisania mechanizmów wykrywania DMMP przez ftalocyjaniny oraz struktury hybrydowe oparte o ftalocyjaniny, pallad i tlenek palladu. Zastosowana metodologia składała się z części teoretycznej i eksperymentalnej. W części teoretycznej wykorzystano metody chemii kwantowej do zamodelowania adsorpcji DMMP na badanych strukturach sensorowych. Do weryfikacji wyników teoretycznych posłużyły metody eksperymentalne, takie jak: spektroskopie fotoemisyjne (XPS i UPS), spektroskopia termodesorpcji oraz pomiar odpowiedzi sensorowych metodą rezystancyjną. Badania zostały wykonane dla dwóch grup struktur: dla ftalocyjaniny wodorowej (H2Pc) z palladem (Pd) i tlenkiem palladu (PdO) oraz dla ftalocyjanin metali. W pierwszej kolejności określono mechanizm sensorowy dla struktury H2Pc/Pd/PdO, która wykazała czułość na DMMP w temperaturze pokojowej. Wyniki modelowania teoretycznego wykazały, że DMMP adsorbuje na H2Pc poprzez oddziaływania fizyczne wzmacniane przez pallad zarówno w postaci metalicznej, jak i w postaci tlenku palladu. Oddziaływanie to wywołuje znaczną zmianę momentu dipolowego układu adsorbent-adsorbat, z niewielkim przesunięciem ładunku elektrycznego. Wyniki teoretyczne zostały potwierdzone doświadczalnie w badaniu składu chemicznego powierzchni struktury H2Pc/Pd/PdO i pomiarach odpowiedzi sensorowej. Następnie, w celu optymalizacji struktury sensorowej, zanalizowano mechanizm oddziaływania DMMP z ftalocyjaninami metali, w których DMMP tworzy wiązanie poprzez tlen z centralnym atomem ftalocyjaniny. W wyniku wstępnych obliczeń teoretycznych wybrano ZnPc do szczegółowej analizy mechanizmu sensorowego. Modelowanie adsorpcji DMMP na ZnPc pokazało, że następuje transfer elektronów z cząsteczki DMMP do ftalocyjaniny, przy czym ładunek pozostaje w większości zakumulowany na wierzchniej monowarstwie ZnPc, co prowadzi do powstania silnego dipola powierzchniowego. Wyniki teoretyczne zostały potwierdzone badaniami zmian elektronowych i chemicznych w cienkiej warstwie ZnPc. Dodatkowo, dla ftalocyjanin metali potwierdzono w modelowaniu teoretycznym analogię mechanizmu sensorowego dla sarinu i DMMP.

La présente thèse étudie les nanoparticules de ZnO incorporées dans une matrice d'acide polyacrylique (PAA) mésosphérique synthétisée via un protocole d'hydrolyse. La structure hybride mésosphérique de ZnO / PAA a précédemment démontré son efficacité pour émettre de la lumière visible dans une large gamme, qui résulte des défauts intrinsèques de niveaux profonds dans les nanocristaux de ZnO. Pour modifier davantage le spectre de photoluminescence (PL) et améliorer le rendement quantique de PL (PL QY) du matériau, le ZnO dopé au métal et le ZnO / PAA revêtu de silice sont fabriqués indépendamment. Au niveau du ZnO dopé avec des éléments métalliques, la nature, la concentration, la taille et la valence du dopant affectent la formation des mésosphères et par conséquent la PL et le PL QY. Les ions plus grands que Zn2+ avec une valence plus élevée ont tendance à induire des mésosphères plus grandes et des nanoparticules de ZnO non incorporées. Le dopage conduit généralement à l'extinction de la PL, mais le spectre PL peut toujours être ajusté dans une large plage (entre 2,46 eV et 2,17 eV) sans dégrader le PL QY en dopant avec de petits ions à une faible concentration de dopage (0,1 %). Concernant le ZnO / PAA revêtu de silice, un revêtement optimal est obtenu, qui dépend corrélativement de la quantité de TEOS et d'ammoniac dans le processus de revêtement. La quantité de TEOS n'affecte pas la structure cristalline de ZnO ou le spectre PL du matériau, mais une concentration élevée d'ammoniac peut dégrader les mésosphères de PAA et épaissir la couche de silice. Une fine couche de silice qui n'absorbe pas trop de lumière d'excitation mais recouvre complètement les mésosphères s'avère être la plus efficace, avec une amélioration drastique du PL QY d’un facteur six. En ce qui concerne l'application, les matériaux souffrent d’une dégradation thermique à des températures élevées jusqu'à 100 °C, auxquelles les diodes électroluminescentes blanches (WLEDs) fonctionnent généralement. Cependant, le ZnO / PAA revêtu de silice induit une intensité d'émission plus élevée à température ambiante pour compenser la dégradation thermique
The present thesis studies ZnO nanoparticles embedded in a mesospheric polyacrylic acid (PAA) matrix synthesized via a hydrolysis protocol. The mesospheric ZnO/PAA hybrid structure was previously proved efficient in emitting visible light in a broad range, which results from the deep-level intrinsic defects in ZnO nanocrystals. To further tune the photoluminescence (PL) spectrum and improve the PL quantum yield (PL QY) of the material, metal-doped ZnO and silica-coated ZnO/PAA are fabricated independently. For ZnO doped with metallic elements, the nature, concentration, size and valence of the dopant are found to affect the formation of the mesospheres and consequently the PL and PL QY. Ions larger than Zn2+ with a higher valence tend to induce larger mesospheres and unembedded ZnO nanoparticles. Doping generally leads to the quenching of PL, but the PL spectrum can still be tuned in a wide range (between 2.46 eV and 2.17 eV) without degrading the PL QY by doping small ions at a low doping concentration (0.1 %). For silica-coated ZnO/PAA, an optimal coating correlatively depends on the amount of TEOS and ammonia in the coating process. The amount of TEOS does not affect the crystal structure of ZnO or the PL spectrum of the material, but high concentration of ammonia can degrade the PAA mesospheres and thicken the silica shell. A thin layer of silica that does not absorb too much excitation light but completely covers the mesospheres proves to be the most efficient, with a drastic PL QY improvement of six times. Regarding the application, the materials suffer from thermal quenching at temperatures high up to 100°C, at which white light emitting diodes (WLEDs) generally operates. However, silica-coated ZnO/PAA induces higher emission intensity at room temperature to make up for the thermal quenching

The aim of investigating the 2D PbX6 inorganic organic hybrids was to study octahedral distortions, short interlayer spacing’s, and the effect of functionalized aliphatic’s terminal halogen on idealizing or destabilizing the octahedral arrangements and their effect on the band gap of the single layer 2D hybrid systems. It was found that the PbX6 metal centred distortions do display some impact on the band gap, the greater the distortion experienced in the Ieq-Pb-Ieq cis bond angles, the wider the band gap, as we suspect a decrease in I 5p antibonding character which lowers the top of the valence band. The terminal halogen interaction specifically in (BrC2)PbI4, clearly displayed some Br 4p/s character at the bottom of the conduction band, which may further explain the reduction of the band gap of this compound. This in conjunction with the shorter interlayer spacing serve to stabilize more idealized bridging angles, as seen in both the lead iodide and bromide analogues. In the short interlayer spacing compounds large idealizations of the Pb-X-Pb bridging angles are observed however display a large metal centred octahedral distortions in order accommodate the spatial occupation of the lone pair on lead. It was generally observed that the lead bromide hybrids appear to have a greater sensitivity to exciton lattice interactions, which give rise to red shifted emissions and absorptions with decreasing temperature. Structurally this behaviour is counterintuitive; because the structures increase in inorganic distortions with decreasing temperature and therefore a blue shift in the exciton absorption is expected. It should be noted that compounds displaying this phenomenon most, (C4, C6, C7)PbBr4 do display a large amount of structural disorder in their lower temperature phases. In the 1D systems investigated further structure to property correlations were made. Optically it was found that unlike the corner-shared perovskite type 1D wires of [NH2C(I)=NH2]3PbI5 and [CH3SC(=NH2)NH2]3PbI5 the first exciton absorption of the octahedral face sharing wires of (A)PbI3 appear to be largely insensitive to the inorganic structural distortions experienced as a result of the low temperature phase transitions. In one instance however a low temperature phase transition did result in a polaron emission which was directly related to a discontinuity in the inorganic wires. More generally experimental links between the STE luminescence emissions and the inter-wire spacing, organic dielectric constant, and the density of the crystal, were shown to influence the STE lattice interactions to a greater degree. This effect is increased through a decrease in crystal density and organic dielectric constant, with an associated increase in the inter-wire spacing. Therefore as the exciton lattice interactions increase, a red shift in the STE emissions is observed. In another series of systems strong 1- and interactions were present in particularly two 1D charge transfer compounds. It was noted that the inorganic wires promote interactions between the organic templates as has also been established in literature. Structurally it was also observed that the CT transitions of these compounds begin to largely coincide with the STE emission arising from the inorganic wire. Even though the CT compounds structurally have strong interactions the current experiments do not ascertain to what degree this interaction assists in electron transport. It was also established that as intermolecular interactions are absent in previously published MV and Et compounds with the dominant CT interaction was the I…N interaction which functions over a large range (4.9A). This long distance is substantiated from the strong covalent character of the I…N interaction observed in IR experiments completed on (MV)Pb2I6. It was also observed in our compounds that the position of the LUMO of the organic cation relative to the valence band of the inorganic wires appears to be largely dependent on the N…I distance and largely independent of the electron accepting templates HOMO-LUMO gap. The increased wire thickness observed in these compounds does appear to display a pronounced effect on the PL emissions as seen in three chain wide wires produced. The thicker chains begin to allow higher energy emission’s to occur i.e. the desired first exciton emission begins to become favored due to the relaxing of the wires spatial confinement on the electron-hole’s orbit. Further investigations are needed into even thicker chain wires, in order to ascertain the ideal size of the wire to obtain the desired high energy first exciton emission. To date the wire thickness that does give rise to the first exciton emission appears to still need at least six coordinated PbI6 octahedral units.

ZnO nanostructures are excellent candidates for use in the production of functional devices because to their low toxicity, robust thermal stability, excellent corrosion resistance, biocompatibility, high specific surface area, and high conductivity. In this chapter we have discussed the various nanostructures of ZnO and their kind, synthesis of hybrid ZnO nanostructure, modification in nanostructure of ZnO, Hybrid nanostructure of ZnO. In addition, we have discussed the various methods like Sol-gel method, Hydrothermal method and Green Synthesis method in detail for the synthesis of ZnO nanostructures. The effect of these methods on variation of nanostructures have been discussed in detail. It has been observed that because of its great sensitivity to the chemical environment, ZnO nanostructures have been extensively used in sensing applications. Also, the ZnO nano structures have been widely used in light emitting diodes and in solar cells because of its semiconducting nature. The ZnO is a n-type semiconductors and has a perfect bandgap of 3.37eV for its use in solar cell applications. Thus, this chapter provides a detailed discussion about the various nano structures of ZnO, the synthesis methods and various applications.

Transparent conducting oxides (TCO) are semiconducting materials that are electrically conductive as well as optically transparent thus making them suitable for application in photovoltaics, transparent heat transfer windows, electrochromic windows, flexible display, and transparent electronics. One of the methods to enhance the conductivity of metal oxides is doping, however, it can adversely affect the optical transparency of metal oxide. Aluminum (Al) doped zinc (Zn) oxide (AZO) is an important TCO material whose optoelectronic properties heavily rely on the Al doping level. There are various methods to develop AZO thin films. However, since Al and Zn are high vapor pressure materials, and their precise content control isn’t that easy, that’s why we dedicated this study to devise a facile method of Al doping into the ZnO structure. We report a twostep synthesis route to develop AZO thin films over glass substrates. Sub stoichiometric zinc oxide (ZnOx) thin films were sputter deposited over glass employing RF magnetron sputtering at 70W and 9 x 10-3 Torr Ar pressure. To mitigate Zn losses during annealing at 450 °C, the films were first oxidized up to 200 °C in air so as to convert ZnOx into stoichiometric ZnO. To incorporate Al into the ZnO structure, Al was spin coated on top of ZnO from its stabilized sol of 0.07 molar aluminum nitrate nonahydrate in ethanol. The samples were subsequently annealed at 450 °C for 2h in air with a controlled heating ramp of 3 °C/min. The film morphology, microstructure, electronic, and optical characteristics were explored employing scanning electron microscopy, energy dispersive x-ray spectroscopy, Hall effect measurements, and UV-Vis-NIR spectrophotometry, respectively. We found that both the Al and oxygen (O) content affect the optoelectronic behavior of AZO. Even without Al doping, O deficient samples were found to be sufficiently conductive, however, the ZnOx is less transparent relative to O rich stoichiometric ZnO. Furthermore, if ZnOx is annealed at higher temperatures, it causes Zn losses, since Zn is a relatively high vapor pressure material. It degrades the film morphology as well. Once we have ZnO we can confidently treat it at 450 °C to allow Al diffusion into the interiors of the ZnO film. We found that AZO produced via this method is sufficiently conductive as well as transparent.