Interdiffusion in InGaAs/GaAs and InGaAs/GaAsP quantum wells

The shape of In0.22Ga0.78As single quantum wells (SQW) grown by metal-organic vapour phase epitaxy (MOVPE) is changed by rapid thermal annealing (RTA). Samples with GaAs barriers were compared with strain-compensated ones with GaAs0.82P0.18 barriers using high-resolution X-ray diffraction (HRXRD), Auger electron spectroscopy (AES) and photoluminescence spectroscopy (PL). After annealing, the PL wavelength is decreased and the luminescence intensity increased. In bare strain-compensated layers, In diffusion is slightly reduced at 850 °C annealing temperature. Encapsulation with SiO2 leads to an increase of the In diffusion up to a factor of 10. In this case, the diffusion process is dominated by vacancies and strain compensation is no longer effective.