Detailed study of amorphous silicon ultraviolet sensor with chromium silicide window layer

In this paper, we present a detailed investigation of an amorphous silicon sensor for the detection of ultraviolet (UV) radiation. The device is an n-i-p stacked structure with a grid-patterned top metal contact through which the incident radiation reaches the active layers. The performances of the sensor have been enhanced by using a very thin chromium silicide (CrSi) film formed on top of the p-doped layer. In particular, this film enhances the surface conductivity, reducing the effect of the self-forward bias that occurs in the device due to the high resistivity of the p-doped layer. As a result, the sensitivity and the linearity of the response increase, reaching a responsivity above 60 mA/W at 254.3 nm. Furthermore, the CrSi layer leads to a stable device because it hides the effect of the p-doped layer resistivity variation under UV radiation. The comparison between two sets of devices with different grid geometries, one with and one without the CrSi film, demonstrates the effectiveness of the alloy film.