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.