Effect of Heat Treatment on Gallium Arsenide Crystals III. Electrical Properties of Thermally Converted p-Type Crystals

Electrical properties were measured from 77° to 400°K for p -GaAs crystals obtained by heat treatment of melt-grown undoped n -GaAs crystals in arsenic vapor. Temperature dependence of hole concentration was best explained with a double acceptor level scheme, in which the first and the second ionization energies are about 0.13 eV and 0.25 eV, respectively. This double acceptor is a newly revealed one probably related to some native defects, and differs from the acceptors present before heat treatment, which seem to be more shallow single acceptors. Analysis of Hall mobility showed that the most dominant scattering mechanism for holes is the polar optical scattering, next the non-polar scattering, and then the deformation potential scattering. The scatterings by ionized impurities and space charge regions are not important in p -GaAs.