Profiling of deep impurities by persistent photocurrent measurements

Abstract

A method to obtain the volume density Z of deep impurities in semiconductors versus their spatial depth is described. Z is derived by measuring the increase of the photoinduced persistent sheet density of carriers Δ(nd) in a conductive layer as a function of incident photon dose Q. The slope of the Δ(nd) = f(log Q) curve depends upon the concentration profile of the deep traps in the substrate beneath the conductive layer, as is demonstrated by experiments using GaAs.