Non-Equilibium Al-Ga interdiffusion in MOCVD reactor annealed AIGaAs quantum well heterostructures

Abstract

AlGaAs-GaAs quantum well heterostructures have been annealed in an atmospheric pressure MOCVD reactor under an AsH₃/H₂ ambient. Photoluminescence spectra show a uniform and reproducible increase in the effective quantum well band-gap. Energy shift data indicate that Al-Ga interdiffusion occurs under “non-equilibrium” conditions resulting in depth-dependent Al-Ga interdiffusion such that quantum wells close to the surface disorder less than those further away. Activation energies vary from approximately 5.1–5.2 eV for the “equilibrium” case to 3.2–3.6 eV for the “non-equilibrium” case. These results suggest that caution must be exercised in using reported activation energies to characterize Al-Ga interdiffusion for photonic device fabrication.