Spectral responses of Te-doped a-Se high-gain avalanche rushing amorphous photoconductor (HARP) films for a solid state image sensor

Abstract

In this paper, spectral responses of Te-doped a-Se HARP (High-gain Avalanche Rushing amorphous Photoconductor) thin films for a solid state image sensor have been reported. Te concentrations of Te-doped layer in a-Se HARP thin film were 15 wt% and 26 wt%, and thicknesses of Te-doped layer were 60 nm, 90 nm, and 120 nm. Spectral responses of Te-doped a-Se HARP films were investigated at bias voltages of 40 V and 60 V. Relative sensitivity and quantum efficiency of a-Se HARP films at 60 V were found to be improved by the increase of Te-doped layer thickness. This improvement is explained by the increased photogeneration efficiency at long wavelength region by the increase of Te-doped layer thickness and avalanche multiplication of the photogenerated carriers at a high electric field.