Detection of Selenium Clustering in GaAs by Transmission Electron Microscopy

Abstract

Direct evidence has been found for the existence of coherent particles and small precipitates in bulk Se‐doped GaAs (n=2×10¹⁸ cm⁻³) and in Se‐doped, vapor‐grown epitaxial GaAs (n=4×10¹⁸; 1×10¹⁹ cm⁻³). Data obtained from moiré fringe contrast indicate a probable particle composition of Ga₂Se₃. In samples with more than 2×10¹⁸ carriers cm⁻³, the major part of the total Se content is in the form of particles, and this accounts for the difference between the total Se concentration and the electrically active Se concentration. Diffusion in the solid can account for particle growth in the Bridgman‐grown crystal, but not in the vapor‐grown epitaxial material.