Photoluminescence measurements of Zn-doped Ga1−xAlxAs grown by metalorganic chemical vapor deposition

Abstract
We have investigated the photoluminescence properties of Zn‐doped Ga1−xAlxAs grown by metalorganic chemical vapor deposition (MOCVD). The photoluminescence spectra exhibit weak bound‐exciton lines, donor–acceptor pair transitions, free‐to‐bound excitons, and low energy broad bands. The Zn acceptor ionization energy is determined from the free‐to‐bound transitions as a function of aluminum concentration x up to 0.46. Two low energy bands have been observed in Zn‐doped Ga1−xAlxAs. One is at ∼1.65 eV and is identified as due to the ZnGa–VAs complex. Another band has been observed at ∼1.81 eV from samples with x near or beyond the crossover. It is well separated from the band edge, but its origin is not yet well understood.