Electronic properties of native deep-level defects in liquid-phase epitaxial GaAs

GaAs grown under Ga-rich conditions often contains two dominant deep levels, sometimes referred to as the A and B levels. The authors have investigated the electronic properties of these levels in n-type and p-type material. The apparent activation energies for thermal hole emission were measured over eight orders of magnitude of thermal emission rate, and found to be 0.40 eV for level A and 0.70 eV for level B after the T 2 correction. All four optical cross sections have been determined. The thresholds for electron excitation are 1.15 and 0.90 eV for the A and B levels, respectively, at 80K. A photocapacitance method is used to demonstrate that the two levels are coupled and thus due to one single defect. The electronic properties, in combination with the conditions under which the defect is formed, lead to the suggestion that the defect may be the Ga As antisite.