Delineation of pn junctions by scanning tunneling microscopy/ spectroscopy in air and ultrahigh vacuum

Abstract

Lateral dopant profiling of cleaved, passivated abrupt GaAs pn junctions using scanning tunneling microscopy/spectroscopy is demonstrated both in ultrahigh vacuum and air. A combination of forward- and reverse-bias imaging and position-dependent tunneling spectroscopy makes it possible to delineate the metallurgical junction location of abrupt asymmetric n+p and symmetric n+p+ junctions. The experimental results are shown to be consistent with simulations based on the metal–insulator–semiconductor band-bending model when surface states and bulk transport through the pn junction are properly taken into account in the calculations.