Nanometer-scale imaging of potential profiles in optically excited <i>n</i>-<i>i</i>-<i>p</i>-<i>i</i> heterostructure using Kelvin probe force microscopy

Abstract

We report on measurements of the potential profile of a GaAs/AlGaAs n-i-p-i multiple quantum well structure using a scanning Kelvin probe force microscope (KFM). Using this novel technique we directly measure with meV precision and sub-100 nm spatial resolution the potential difference between n-i-p-i layers with and without external optical excitation. The measured potential profiles, which have not been directly imaged previously, agree well with potential profiles calculated for optically excited n-i-p-i structures, but modified by band bending effects at the surface.