Effect of initial surface reconstruction on the GaS/GaAs(001) interface

We have used photoluminescence of a GaAs/Al0.3Ga0.7As near-surface quantum well structure to study the quality of the interface between GaAs and GaS d eposited in ultrahigh vacuum (UHV) using [(Bu-t)GaS](4). In addition to the luminescence of the near-surface and the deep/reference quantum wells, lum inescence was observed for the GaAs cap following the deposition of 100 Ang strom of GaS. This additional feature demonstrates the high quality GaS/GaA s interface achievable through the UHV deposition of this precursor. The ra tios of the integrated luminescence intensity of both the GaAs cap and the near-surface GaAs quantum well to the deep/reference quantum well indicate that there are fewer GaS/GaAs interface states for deposition on the Ga-ric h GaAs(001)-(4 x 2)/(2 x 6) surface compared to deposition on the As-rich G aAs(001)-(2 x 4) surface. Furthermore, GaS passivated samples exposed to am bient conditions for eight months exhibit no luminescence degradation for t he near-surface quantum well confirming that these films provide adequate p assivation longevity. (C) 1999 American Institute of Physics. [S0003-6951(9 9)05147-5].