The effect of surface passivation of GaAs-based cylindrical mesa structures on their optical properties

The optical properties of GaAs-based cylindrical mesa-structures were studied before and after passivation using hydrogen plasma treatment followed by atomic layer deposition of an Al$_2$O$_3$ layer. The In$_{0.2}$Ga$_{0.8}$As/GaAs quantum well and the GaAs/AlAs superlattice were used as the light-emitting region of the mesa structures. The diameter of the mesas varied from 3 to 20 $\mu$m. The result of passivation was an 8-fold increase in the photoluminescence intensity of 9 $\mu$m-diameter mesa at room temperature, and time-resolved photoluminescence studies of such mesa structures demonstrated an increase in charge carrier lifetime from 0.13 to 0.9 ns.