Type conversion in electron-irradiated GaAs

Abstract

The unambiguous type conversion of GaAs by electron irradiation is reported here for the first time. Several high‐quality n‐type vapor‐phase epitaxial layers (ρ?3 Ω cm and μ?7000 cm²/V sec at 300 K) were converted by 1‐MeV electrons to high‐quality p‐type layers (ρ?30 Ω cm and μ?400 cm²/V sec). Temperature‐dependent Hall‐effect data show energy levels at 0.5, 0.3, and about 0.1 eV above the valence band. Evidence is presented to indicate that the failure of some of our samples (and, perhaps, other samples reported in the literature) to convert to low‐resistivity p type is due to a rather high concentration of as‐grown deep levels which pin the Fermi level near midgap.