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1.
Structural, optical and electrical properties of CuIn5S8 thin films grown by thermal evaporation have been studied relating the effects of substrate heating conditions of these properties. The CuIn5S8 thin films were carried out at substrate temperatures in the temperature range 100-300 °C. The effects of heated substrate on their physico-chemical properties were investigated using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), optical transmission and hot probe method. X-ray diffraction revealed that the films are strong preferred orientation along the (3 1 1) plane upon substrate temperature 200 °C and amorphous for the substrate temperatures below 200 °C. No secondary phases are observed for all the films. The composition is greatly affected by heated substrate. From the optical transmission and reflection, an important absorption coefficient exceeds 105 cm−1 at 800 nm was found. As increasing the substrate temperature, the optical energy band gap decreases from 1.70 eV for the unheated films to 1.25 eV for the deposited films at 300 °C. It was found that CuIn5S8 thin film is an n-type semiconductor at 250° C.  相似文献   

2.
Nanocrystalline indium oxide (INO) films are deposited in a back ground oxygen pressure at 0.02 mbar on quartz substrates at different substrate temperatures (Ts) ranging from 300 to 573 K using pulsed laser deposition technique. The films are characterized using GIXRD, XPS, AFM and UV-visible spectroscopy to study the effect of substrate temperature on the structural and optical properties of films. The XRD patterns suggest that the films deposited at room temperature are amorphous in nature and the crystalline nature of the films increases with increase in substrate temperature. Films prepared at Ts ≥ 473 K are polycrystalline in nature (cubic phase). Crystalline grain size calculation based on Debye Scherrer formula indicates that the particle size enhances with the increase in substrate temperature. Lattice constant of the films are calculated from the XRD data. XPS studies suggest that all the INO films consist of both crystalline and amorphous phases. XPS results show an increase in oxygen content with increase in substrate temperature and reveals that the films deposited at higher substrate temperatures exhibit better stoichiometry. The thickness measurements using interferometric techniques show that the film thickness decreases with increase in substrate temperature. Analysis of the optical transmittance data of the films shows a blue shift in the values of optical band gap energy for the films compared to that of the bulk material owing to the quantum confinement effect due to the presence of quantum dots in the films. Refractive index and porosity of the films are also investigated. Room temperature DC electrical measurements shows that the INO films investigated are having relatively high electrical resistivity in the range of 0.80-1.90 Ωm. Low temperature electrical conductivity measurements in the temperature range of 50-300 K for the film deposited at 300 K give a linear Arrhenius plot suggesting thermally activated conduction. Surface morphology studies of the films using AFM reveal the formation of nanostructured indium oxide thin films.  相似文献   

3.
Polycrystalline zirconium tin titanate (Zr0.8Sn0.2TiO4, ZST) thin films with thickness of 81 nm were deposited successfully along the (1 0 0) on a p-type Si substrate by an improved sol-gel method. The deposited films were crystallized when annealing temperature was up to 450 °C. The thickness and compositions of the interface layer between the ZST films and Si substrate were identified by high-resolution transmission electron microscope (HRTEM). The electrical properties such as leakage current density, flat-band voltage and capacitance of the films were measured and discussed. Furthermore, the mechanism of the leakage current was also investigated.  相似文献   

4.
Si doped zinc oxide (SZO, Si3%) thin films are grown at room temperature on glass substrates under argon atmosphere, using direct current magnetron sputtering. The influence of the target substrate distances on structure, morphology, optical and electrical properties of SZO thin films is investigated. Experimental results show that the target substrate distances have a significance impact on the growth rate, crystal quality and electrical properties of the films, and have little impact on the optical properties of the films. SZO thin film samples grown on glasses are polycrystalline with a hexagonal wurtzite structure and have a preferred orientation along the c-axis perpendicular to the substrate. When the target substrate distance decreases from 76 to 60 mm, the degree of crystallization of the films increased, the grain size increases, and the resistivity of films decreases. However, when the distance continuously decreases from 60 to 44 mm, the degree of crystallization of the films decreased, the grain size decreases, and the resistivity of the films increases. SZO(3%) thin films deposited at a target substrate distance of 60 mm show the lowest resistivity of 5.53 × 10−4 Ω cm, a high average transmission of 94.47% in the visible range, and maximum band gap of 3.45 eV under 5 Pa of argon at sputtering power of 75 W for sputtering time of 20 min.  相似文献   

5.
ZnO thin films with the thickness of about 15 nm on (0 0 0 1) sapphire substrates were prepared by pulsed laser deposition. X-ray photoelectron spectroscopy indicated that both as-grown and post-annealed ZnO thin films were oxygen-rich. H2 sensing measurements of the films indicated that the conductivity type of both the unannealed and annealed ZnO films converted from p-type to n-type in process of increasing the operating temperature. However, the two films showed different conversion temperatures. The origin of the p-type conductivity in the unannealed and annealed ZnO films should be attributed to oxygen related defects and zinc vacancies related defects, respectively. The conversion of the conductivity type was due to the annealing out of the correlated defects. Moreover, p-type ZnO films can work at lower temperature than n-type ZnO films without obvious sensitivity loss.  相似文献   

6.
Pure and Nb-doped titanium oxide thin films were grown on sapphire substrates by pulsed-laser deposition in vacuum (10−7 mbar). The PLD growth leads to titanium oxide thin films displaying a high oxygen deficiency (TiO1.5) compared with the stoichiometric TiO2 compound. The structural and electrical properties (phase, crystalline orientation, nature and concentration of charge carriers, etc.) of these titanium oxide films were studied by XRD measurements and Hall effect experiments, respectively. The undoped TiO1.5 phase displayed a p-type semiconductivity. Doping this titanium oxide phase with Nb5+ leads to an n-type behaviour as is generally observed for titanium oxide films with oxygen deficiency (TiOx with 1.7 < x < 2). Multilayer homojunctions were obtained by the stacking of TiO1.5 (p-type) and Nb-TiO1.5 (n-type) thin films deposited onto sapphire substrates. Each layer is 75 nm thick and the resulting heterostructure shows a good transparency in the visible range. Finally, the I-V curves obtained for such systems exhibit a rectifying response and demonstrate that it is possible to fabricate p-n homojunctions based only on transparent conductive oxide thin films and on a single chemical compound (TiOx).  相似文献   

7.
p-Type nickel oxide thin films were prepared by sol-gel method, and their structural, optical and electrical properties were investigated. The Ni(OH)2 sol was formed from nickel (II) acetate tetrahydrate, Ni(CH3COO)2·4H2O, in a mixture of alcohol solution and poly(ethylene glycol), and deposited on an ITO substrate by spin coating followed by different heat treatments in air (50-800 °C). The formation and composition of NiO thin film was justified by EDX analysis. It is found that the thickness of the NiO film calcined at 450 °C for 1 h is about 120 nm with average particle size of 22 nm, and high UV transparency (∼75%) in the visible region is also observed. However, the transmittance is negligible for thin films calcined at 800 °C and below 200 °C due to larger particle size and the amorphous characteristics, respectively. Moreover, the composite electrode comprising n-type TiO2 and p-type NiO is fabricated. The current-voltage (I-V) characteristics of the composite TiO2/NiO electrode demonstrate significant p-type behavior by the shape of the rectifying curve in dark. The effect of calcination temperature on the rectification behavior is also discussed.  相似文献   

8.
Titanium-doped cadmium oxide thin films were deposited on quartz substrate by pulsed laser deposition technique. The effect of substrate temperature on structural, optical and electrical properties was studied. The films grown at high temperature show (2 0 0) preferred orientation, while films grown at low temperature have both (1 1 1) and (2 0 0) orientation. These films are highly transparent (63-79%) in visible region, and transmittance of the films depends on growth temperature. The band gap of the films varies from 2.70 eV to 2.84 eV for various temperatures. It is observed that resistivity increases with growth temperature after attaining minimum at 150 °C, while carrier concentration continuously decreases with temperature. The low resistivity, high transmittance and wide band gap titanium-doped CdO films could be an excellent candidate for future optoelectronic and photovoltaic applications.  相似文献   

9.
Ag-doped ZnO (ZnO:Ag) thin films were grown on glass substrates by E-beam evaporation technique. The structural, electrical and optical properties of the films were investigated as a function of annealing temperature. The films were subjected to post annealing at different temperatures in the range of 350-650 °C in an air ambient. All the as grown and annealed films at temperature of 350 °C showed p-type conduction. The films lost p-type conduction after post annealing treatment temperature of above 350 °C, suggesting a narrow post annealing temperature window for the fabrication of p-type ZnO:Ag films. ZnO:Ag film annealed at 350 °C revealed lowest resistivity of 7.25 × 10−2 Ω cm with hole concentration and mobility of 5.09 × 1019 cm−3 and 1.69 cm2/V s, respectively. Observation of a free-to-neutral-acceptor (e,Ao) and donor-acceptor-pair (DAP) emissions in the low temperature photoluminescence measurement confirms p-type conduction in the ZnO:Ag films.  相似文献   

10.
The properties of chalcogenides that are most important for applications as infrared transmitting materials are reported and their mutual relationships are given. Si5Se80In15 films were produced by means of thermal evaporation. The refractive index and the optical energy gap were determined by transmission measurements. Parameters considered in this study are density, molar volume, transition temperatures, electrical properties, infrared transmission, extinction coefficient and refractive index. This composition has no extrinsic and intrinsic absorption between 14 and 20 μm and the value of absorption coefficient is estimated lower than 10−3 cm−1 at 10.6 μm. This glass is also suitable for infrared optical elements. A p-n junction is observed due to evaporated thin film of alloy on p-type Ge substrate.  相似文献   

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