Effect of Deposition Temperature on the Physical Performance of n-ZnO/p-Si Heterojunction

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.