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

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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.