NANOMETER-SCALE IMAGING OF POTENTIAL PROFILES IN OPTICALLY-EXCITED N-I-P-I HETEROSTRUCTURE USING KELVIN PROBE FORCE MICROSCOPY

We report on measurements of the potential profile of a GaAs/AlCaAs n- i-p-i multiple quantum well structure using a scanning Kelvin probe fo rce microscope (KFM). Using this novel technique we directly measure w ith meV precision and sub-100 nm spatial resolution the potential diff erence between n-i-p-i layers with and without external optical excita tion, The measured potential profiles, which have not been directly im aged previously, agree well with potential profiles calculated for opt ically excited n-i-p-i structures, but modified by band bending effect s at the surface. (C) 1995 American Institute of Physics.