Effects of thermal annealing on the diode properties and space charge limited conduction of the physical vapor-deposited n-ZnS/p-Si(100) heterojunctions

Abstract

The effects of thermal annealing on the device performance of the as-grown n-ZnS/p-Si(100) deposited via home-made physical vapor deposition machine was examined through the analysis of the I-V characteristics at room temperature under dark current measurements. Both as-grown and thermally annealed samples were found to exhibit a rectifying diode-like behavior and revealing that under reverse bias, avalanche of leakage current flow were observed at voltages greater than -15 V in the as-grown sample. An almost completely disappearing leakage current flow and a dramatic increase of forward current were exhibited after thermal annealing. Exposure of the samples to different wavelengths of light (200-800 nm) showed the thermally annealed sample to have a promising photodetection property in the UV (∼339 nm) and in some wavelengths in the visible range (500, 550 and 600 nm). The current transport of the as-grown and thermally annealed n-ZnS/p-Si(100) heterojunctions fabricated were dominantly space-charge limited conduction with possible presence of defect states in the surface and in the bulk of the material.