Carrier transport mechanisms and photodetector characteristics of Ag/TiOPc/p-Si/Al hybrid heterojunction

Hybrid heterojunction device was fabricated by employing a p-type Si and a thin film of titanyl phthalocyanine (TiOPc). The dark current density-voltage characteristics of the fabricated Ag/TiOPc/p-Si/Al heterojunction were investigated at different temperatures ranging from 294 to 375 K to determine the carrier transport mechanisms. At low forward bias, the current was found to follow the thermionic emission mechanism, while at high forward bias, the space charge limited current controlled by exponential trap distribution was found to be the dominated mechanism. The ideality factor and the barrier height were determined. At reverse bias, the conductivity was interpreted in terms of the Schottky effect. The interface state density was determined from the current-voltage characteristics. Also, the photodetector characteristics were studied for the fabricated device under illumination of near-infrared 805 nm laser. The responsivity, external quantum efficiency, and detectivity were determined. The photodetector was found to have a rise time of about 23 µs.