n-ZnO/p-Si heterojunctions for photosensor applications

Photodetectors functioning in the short wavelength (from 300nm to 500 nm) ultraviolet part are paramount devices that can be applied in civil and military applications. In this work, we have demonstrated the n-ZnO/p-Si heterojunction photodiodes. A zinc (Zn) metal was coated on silicon (Si) substrate from high purity Zn metal targets by dc sputtering deposition technology. Subsequent, the Zn thin films were then annealed in the conventional furnace annealing temperatures under flowing oxygen gas environment. As a result of current-voltage (I-V) measurements, the data analysis of I-V characteristics of the device exhibited the ordinary excellent rectifying behavior for the heterojunctions. The UV photocurrent versus reverse-bias voltage measurement was done using an LTV lamp. Under a dark condition, the n-ZnO/p-Si diodes exhibit intense rectifying behavior characterized by the I-V measurement. For a reverse bias, high photocurrent is acquired when the crystalline grade of n-type ZnO film is good sufficient to transmit the illuminated into p-Si.