Identification and Quantification of Defects in Highly Si-Doped GaAs by Positron Annihilation and Scanning Tunneling Microscopy

Defects in highly Si-doped GaAs were identified and their concentration determined by combining positron lifetime spectroscopy with scanning tunneling microscopy. We observed with increasing Si-doping concentration an increasing concentration of a deep positron trap identified as S${\mathrm{i}}_{\mathrm{Ga}}$-donor–Ga-vacancy complex. The concentration of shallow positron traps increased with the Si concentration too. The shallow traps are found to be S${\mathrm{i}}_{\mathrm{As}}$ acceptors and Si clusters.