Hole injection in AlGaAs Schottky barriers: Influence on the DX center occupation

It is shown that current instabilities, which are frequently observed at low temperatures in forward biased Schottky barriers on n-type AlGaAs, result from changes in the distribution of negatively charged donors (DX centers) near the metal contact. These changes cannot be ascribed to sample-heating effects, but they originate from hole injection in the barrier during forward biasing. The dominant mechanisms which are expected to induce the observed distortions in the DX center profile are (i) direct capture of the injected holes by the DX center and (ii) radiative electron-hole recombination resulting in DX center photoionization. The role of the two mechanisms is discussed