Abstract
Abstract Metal–semiconductor contacts on highly Be-doped GaAs layers grown by molecular beam epitaxy are used to examine deep electronic states by deep-level transient Fourier spectroscopy. Two hole traps at 0.40 and 0.70 eV are found, which are associated with the GaAs (Ga atom on As site) defect. The concentration versus depth profile demonstrates that the intrinsic defect is formed in a 100 nm thick layer near the as-grown surface. Our experimental results confirm thermodynamical calculations for nearly Ga-rich conditions during growth. The GaAs formation energy strongly decreases, when the Fermi level is shifted from the valence band edge to midgap position. The concentration versus depth profile therefore reflects the change of the GaAs formation energy near the GaAs surface during growth. The energy to form GaAs defects at the surface of p-type GaAs is determined to be 1.1 eV, in full agreement with theoretical results.
Published Version
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