Origin of the nonexponential thermal emission kinetics of DX centers in GaAlAs

Direct evidence has been found, via hydrostatic pressure experiments, that the random distribution of Al and Ga atoms (alloy broadening) is the main cause of the nonexponential behavior of thermal emission processes from DX centers in Ga1-xAlxAs alloys (0.19≤x≤0.74). Isothermal single-shot emission transients at constant capacitance were used to measure the nonexponential behavior. Experimental values of the degree of nonexponentiality at ambient pressure, as a function of the Al content, are in good agreement with an alloy broadening model. When hydrostatic pressure up to 11 kbar is applied, the nonexponential behavior does not change, confirming its independence from variations in the conduction-band structure.