A New Technique of Quantum Well Disordering and its Application to Integrated All-Optical Switches

Abstract

The disordering of GaAs/AlGaAs multiple quantum well (MQW) system has potential applications in optoelectronic devices and integrated circuits. In this paper, we describe a new technique of disordering of GaAs/AlGaAs MQW, which uses the diffusion of group III vacancies generated by etching off the surface oxide. Several sets of samples were prepared under different conditions. One set of samples, A., was left in their as-grown state. The second set of samples, B., was oxidized by heating in air for 30min at 600°C, and then etched in concentrated hydrofluoric (HF) acid for 15min. The acid only etched the oxide, thereby generated group III vacancies on the sample surface. In order to test whether the structures could be protected from disordering, a third set of samples, C., was oxidized by heating, etched and then re-oxidized in H2O2 for 5sec. The above three sets of samples were finally annealed at a temperature of 615°C for 3hr in a tube furnace with a continuous flow of N2 gas. Freshly cleaned GaAs substrate were used to cover the samples in order to minimize As loss. Photoluminescence (PL) results for sample set A show a peak at 820nm, which is exactly the same as the PL spectrum measured from the as—grown sample. In the case of sample set B., the PL emission was blue shifted by 75nm. On the other hand, sample set C did not show any wavelength shift. In this case, the PL spectrum was also identical to the as—grown sample.