Simultaneous potential and dopant mapping at p-n junctions using scanning tunneling microscopy

摘要

Cross-sectional scanning tunneling microscopy is used to map out the potential distribution at GaAs p-n junctions with sub-nanometer resolution and to correlate the potential distribution to a simultaneously obtained dopant distribution. This allows atomic resolution identification of the metallurgical interface, the width of the depletion zone, and the electronic interface defined by the Fermi energy position as well as its pronounced roughness arising from fluctuations in the dopant atom distribution beyond statistical expectations. Furthermore, local scanning tunneling spectroscopy unveils variations in electronic characteristics of local fluctuations of the dopant atom distribution that can be explained by confining potential barriers even at room temperature.