Cadmium oxide (CdO) thin films with low electrical resistivity and higher transparency have been deposited by radiofrequency (RF) magnetron sputtering on glass substrates. Sputtering process was carried out at RF power of 40 W and with varying substrate temperatures. The structural, morphological, electrical, and optical properties of the deposited films are investigated. The structural properties reveals that the as-deposited CdO films shows preferential orientation along (111) plane exhibiting face centered cubic structure. The surface morphology shows that all the films possess well defined grain boundaries with high uniformity. CdO samples deposited at substrate temperature of 150°C with RF power of 40 W exhibits above 95% transparency within the visible wavelength with lower electrical resistivity value in the order of 10−5 Ω·cm. The Raman spectroscopy analysis reveals the possible modes present in CdO films and its dependence on substrate temperature. The comparatively high value of the figure of merit for the optimum sample of CdO deposited at 150°C indicates that these films are suitable for optoelectronic device applications.
ZnO possess distinctive characteristics such as low cost, wide band gap (3.36 eV) and large exciton binding energy (60meV). As the band gap lies in ultra violet (UV) region, ZnO is considered as a novel material for the fabrication of ultra violet light emitting diodes (UV-LEDs). However, ZnO being intrinsic n-type semiconductor the key challenge lies in realization of stable and reproducible p-type ZnO. In the present research dual acceptor group-V elements such as P and N are simultaneously doped in ZnO films to obtain the p-type characteristics. The deposition is made by programmable spray pyrolysis technique upon glass substrates at 697K. The optimum doping concentration of P and N were found to be 0.75 at% which exhibits hole concentration of 4.48 x 10^18 cm-3 and resistivity value of 9.6 Ω.cm. The deposited p-ZnO were found to be stable for a period over six months. Highly conducting n-type ZnO films is made by doping aluminum (3 at%) which exhibits higher electron concentration of 1.52 x 10^19 cm-3 with lower electrical resistivity of 3.51 x 10-2 Ω.cm. The structural, morphological, optical and electrical properties of the deposited n-ZnO and p-ZnO thin films are investigated. An efficient p-n homojunction has been fabricated using the optimum p-ZnO:(P,N) and n-ZnO:Al layers. The current–voltage (I–V) characteristics show typical rectifying characteristics of p-n junction with a low turn on voltage. Electroluminescence (EL) studies reveals the fabricated p-n homojunction diodes exhibits strong emission features in ultra-violet (UV) region around 378 nm.
Cadmium Oxide (CdO) thin films with low electrical resistivity and higher transparency has been deposited by r.f. magnetron sputtering on glass substrates. Sputtering process was carried out at r.f. power of 40W and with varying substrate temperatures. The structural, morphological, electrical and optical properties of the deposited films are investigated. The structral properties reveals that the as-deposited CdO films shows preferential orientation along (111) plane exhibiting face centered cubic structure. The surface morphology shows that all the films possess well defined grain boundaries with high uniformity. CdO samples deposited at substrate temperature of 150°C with r.f. power of 40W exhibits above 95% transparency in the visible region with lower electrical resistivity value in the order of 10-4 Ω.cm. The comparatevely high value of the figure of merit for the optimum sample of CdO deposited at 150°C indicates that these films are suitable for optoelectronic device applications.
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