Main Subjects : Thin films
Performance Analysis of n-ZnO/p-Si Heterojunction Diode as Function of Zinc Oxide Thin Films Thickness
Journal of Education and Science,
2022, Volume 31, Issue 2, Pages 114-127
The n-type Zinc oxide (n-ZnO) nanostructured thin films (TFs) with different thicknesses (211, 325, 433 and 552 nm) were grown onto glass substrates employing the CVD technique at atmospheric pressure. Deposited films were characterized by EDX spectroscopy attached with FE-SEM and XRD techniques to determine the influence of thickness on elemental compositions and crystalline structure of ZnO films, respectively. Also, ZnO TFs were deposited on the p-Si(111) substrates to form different structures of n-ZnO/p-Si heterojunction diodes and then I-V characteristics were studied in the dark. The electrical parameters of the diodes such as rectification ratio (RR), reverse saturation current (Is), ideality factor (), barrier height (b) and series resistance (Rs) were calculated from the I-V measurements. EDX spectra showed that these films were only made from Zn and O elements. XRD patterns presented that the ZnO films possess hexagonal wurtzite structure with preferred orientation along  direction. I-V characteristics of the heterojunction diodes revealed rectification behavior and depend on ZnO TFs thickness. Also, electrical parameters of diodes were affected by the prepared film's thickness. It was found that the crystalline structure of the films and electrical properties of diodes were improved with increasing the thickness of ZnO films. It is noted that the best heterojunction diodes were that prepared with thickness (552 nm), where possess lowest value of ideality factor (3.38) and a series resistance (0.84 k) with a highest rectification ratio (1517), compared with other structures. This study offers a simple model for fabricating diodes from semiconductor films.
Journal of Education and Science,
2020, Volume 29, Issue 2, Pages 118-132
Comparative study of the physical characteristics of n-ZnO/p-Si heterojunction diode has been done as a function of deposition temperature in the range of 300-600 °C. Transparent conducting (TC) Zinc Oxide (ZnO) thin films were deposited by atmospheric pressure chemical vapor deposition (APCVD) technique on the p-Si(100) and glass substrates. Also, the influences of different deposition temperature on the morphology and optical properties of ZnO films were studied. Both the average surface roughness (from 62.8 to 18.8 nm) and the root mean square (from 78.2 to 24 nm) of ZnO films were decreased with the increase in the deposition temperature. Optical transmittance measurement results exhibited good transparency within the visible wavelength range for the films prepared at a temperature above 400 C. The current-voltage (I-V) characteristics of the heterojunction diodes exhibited rectification behavior and depend on the deposition temperature. The electrical parameters of the n-ZnO/p-Si heterojunctions were also affected by the deposition temperature. The diodes prepared at a temperature above 400 C were possessed lower reverse saturation current and high rectification ratio compared to those fabricated at a relatively lower temperature such as 300 C or 400 °C. Such low a temperature grown n-ZnO/p-Si heterojunction diodes with lower reverse saturation current could be suitable for photo-detection applications.