Light Sensitive Properties and Temperature-Dependent Electrical Performance of n-TiO2/p-Si Anisotype Heterojunction Electrochemically Formed TiO2 on p-Si

We report the fabrication, electrical characteristics and light sensitivity of n-TiO2/p-Si heterojunction devices in which the TiO2 layer was grown on p-Si substrates by cathodic electrodeposition. After the structural, morphological, and optical characterization of the deposited metal oxide film, 15 devices were fabricated. One was analyzed by current–voltage (I–V) and capacitance–voltage (C–V) analyses in a wide temperature range. Furthermore, another device was exposed to light and the I–V measurements were analyzed to investigate the light response of the n-TiO2/p-Si heterojunction. The device exhibited a photodiode property such that the reverse bias current value of the heterojunction significantly increased with exposure to the light. Temperature-dependent I–V and C–V measurements of the device showed that the device characteristics depend on both temperature and voltage. Thermionic emission and Norde method were used to evaluate temperature-related I–V measurements. According to the experimental results, it was observed that the barrier height increased [ranging from 0.24 eV (80 K) to 0.76 eV (300 K)] with increasing temperature and the ideality factor decreased [ranging from 4.94 (80 K) to 3.17 (300 K)]. This behaviour was attributed to the inhomogeneous barrier height of the n-TiO2/p-Si.