A study of impurity-free vacancy disordering in GaAs-AlGaAs for improved modeling

A study of the parameters of the process of impurity-free vacancy disordering (IFVD) of GaAs-AlGaAs quantum-well structures is presented. The study includes photoluminescence excitation measurements which show that the as-grown barrier/well interface is better fitted by an exponential profile than a square profile, This has a significant effect on the intermixed diffusion profiles. Also, deep level transient spectroscopy measurements have been conducted on samples that were processed using IFVD, The measurements show an elevated concentration of the trap EL2 in the processed samples, which is known to be related to As antisites. The concentration of such defects agrees with the concentration calculated for IFVD to within an order of magnitude, suggesting a correlation between the point defects required for IFVD and EL2, Finally, temporally and spatially resolved photoluminescence measurements were conducted on processed samples which indicate a factor of 3 reduction in the photogenerated carrier life time after undergoing IFVD. A spatial resolution better than 3 mu m has been observed.