Nanoscale dopant-induced dots and potential fluctuations in GaAs

Abstract

We identified p-type nanoscale dopant-induced dots that are formed by fluctuations of the dopant atom distribution in sufficiently thin GaAs p–n multilayers. Their electronic structure and the resulting potential variations were investigated by cross-sectional scanning tunneling microscopy and spectroscopy as a function of the number of dopant atoms within the dot. We find significant changes in the current–voltage characteristics of the dots compared to spatially nonconfined material, due to a reduced ability to screen the tip’s electric field. This indicates a limited ability to deplete the dots of free holes arising from the presence of confining potentials surrounding the dopant-induced dots.