The electrical properties of GaAs1-xpxalloys from a high-pressure experiment

Abstract

Hall effect measurements at 296k and at hydrostatic pressures up to 15 kbar have been made on se-doped single crystals of GaAs1-xpx, where 0.30?x?0.42. Results have been interpreted in terms of the energies and effective masses of the gamma1c and x1c conduction-band minima. It is shown that such measurements provide a useful method of determining the composition where both bands have equal energies. This is found to occur at x=0.49 +or- 0.02 at an energy of 2.03 +or- 0.02 ev relative to the valence-band maximum. Two impurity levels, for samples with x1c carrier concentrations near 1018 cm-3 have activation energies of 0.04 and 0.10 ev below the x1c minima. Results on stoichiometrically controlled samples indicate that the deeper level may be associated with a gallium vacancy-donor complex. The bowing of x1c minima across the system should be lower than for the gamma1c minimum in agreement with theoretical predictions.