Atomic-scale characterization of highly doped Si impurities in GaAs using scanning tunneling microscopy

Abstract

Characterizing the atomic arrangement and distribution of dopant atoms is important for the fundamental understanding of the effects of doping on the electronic properties of semiconductors. Here, we used scanning tunneling microscopy (STM) to image the dopant species in highly Si-doped GaAs. Based on the distinct features in the STM images, we identified the most common Si species, which enabled the accurate evaluation of the local donor and acceptor concentrations and their in-plane variation across different regions. Systematic analysis of the variation of these properties with the doping concentration and the changes after the post-annealing process allowed atomic-scale information about the detailed behaviors of the Si species to be directly extracted. Our findings provided strong insights into the possible roles of each Si species in modifying the macroscopic electronic properties of GaAs.