Investigation of intermixing induced by sputtering and annealing in multiple quantum well

A thin layer of sputtered SiO2 film was deposited on AlGaAs/AlGaInAs multiple quantum well (MQW) samples and a subsequent rapid thermal annealing (RTA) was carried out. Photoluminescence (PL) studies showed a 60 meV band-gap shift for the AlGaAs/AlGaInAs MQW. An interdiffusion length of 10.7 Å corresponding to the above band-gap shift in the MQW was obtained using transfer matrix method (TMM). An apparent diffusion coefficient was evaluated to be 1.43×10−16 cm2/s. We also calculated the energy levels of the AlGaAs/GaAs MQW with four single wells using TMM and compared the calculated results with the experimental values from the PL measurements. The comparison shows good agreement. To see the influence of RTA condition on PL characteristics of the wells at different depth beneath the surface of the sample, we annealed the SiO2 film covered AlGaAs/GaAs MQW at 650–780 °C for 20–80 s. A subsequent PL measurement shows that the photoluminescence characteristics of the four single quantum wells behave differently with the change of RTA condition. The PL intensities of the wells close to the surface and the bottom of the AlGaAs/GaAs MQW are sensitive to the RTA condition while those of the wells in the middle of the MQW show little variations with the change of RTA conditions.