High-quality molecular-beam epitaxial regrowth of (Al,Ga)As on Se-modified (100) GaAs surfaces

It is shown that high-quality molecular-beam epitaxial (MBE) regrowth of (Al,Ga)As on GaAs can be achieved by chemically passivating the GaAs surface ex situ prior to regrowth with aqueous selenium reagents. Reflection high-energy electron diffraction intensity oscillations show the bidimensional character of the regrowth and high-resolution transmission electron microscopy reveals defect-free regrown interfaces. Photoluminescence intensity from the Se-treated GaAs surfaces on which Al0.5Ga0.5 As is regrown rivals that from an all in situ grown AlGaAs/GaAs interface. The high quality of these regrown interfaces could be attributed to the thermally and chemically stable selenium and oxygen phases that remain bound to GaAs under MBE conditions.