Origin of n≃2 injection current in AlxGa1−xAs heterojunctions

Abstract
We show that the n≃2 current in AlxGa1−xAs heterojunctions is due to surface recombination. The rate of recombination at etched surfaces is evaluated in two photoluminescence experiments. Both of these experiments provide evidence that the rate of surface recombination is proportional to exp(eV/2kT) and has the correct magnitude to account for the measured IV curves. The n≃2 behavior is shown to be a necessary consequence of maintaining equality between surface and depletion layer charge.