Scanning tunneling microscopy and potentiometry at GaAs/AlGaAs heterojunctions

Abstract

In certain problems of electrical transport through condensed matter, it is important to know the potential distribution with nanometer resolution, e.g., at interfaces (Schottky barriers) or pn junctions. Scanning tunneling potentiometry, a new application of scanning tunneling microscopy, is capable of providing this information. The tunnel current is used for simultaneously sensing probe-to-sample distance and local potential. We have used this technique for the localization of semiconductor junctions in cleaved MBE-grown AlGaAs-GaAs laser structures. Among other applications, the electron injection into the active GaAs layer of a heterostructure laser diode was readily observed.