Low dark current and blue enhanced a-Si:H∕a-SiC:H heterojunction n-i-δi-p photodiode for imaging applications

Abstract

This paper presents an a-Si:H∕a-SiC:H heterojunction n-i-δi-p photodiode with low dark current and enhanced short wavelength responsivity suitable for low-level light detection applications. Junction properties and carrier transport are investigated in terms of current-voltage characteristics, photocurrent transient measurements, and spectral photoresponse. It is demonstrated that introduction of a thin (∼40Å) undoped a-SiC:H buffer (δi) at the p-i interface significantly reduces the reverse dark current and recombination losses at this interface. A dark current density of ∼10pA∕cm2 at reverse bias of 1V is achieved for the n-i-δi-p structure, in which the p-type a-SiC:H window layer and the undoped δi buffer layer have a band gap of 2eV.