The EL2-like metastable defect and the n- to p-type transition in silicon planar-doped GaAs

Through photo-Hall measurements at temperatures below about 120 K, we have observed the presence of a deep donor defect, with characteristics similar to those of the EL2 center, in planar-doped GaAs samples grown by molecular beam epitaxy at 300 °C. We have shown that this EL2-like center can account for the remarkable photoreleasing of electrons and holes into the conduction and valence bands, respectively. The two different kinds of carriers accumulate in two spatially separated channels, which can secondarily account for the n- to p-type transition we have observed.