Evidence for negatively charged DX-center in Si-doped AlGaAs from persistent photoconductivity measurements

Persistent photoconductivity experiments were carried out in Si-doped Al xGa 1-xAs at 77 K. The density of persistent free electrons was changed by a factor of 4 to 8. The electron mobilities micro were observed to increase for increasing electron densities n and from the behavior of micro(n) the variation of the ionized scattering impurity densities N i with n was evaluated. The densities N i show little change as compared to n. It is concluded that negatively charged centers are the only or at the least the dominant deep centers related to silicon impurities in AlGaAs.