Periodic lateral structure of Al content modulations in AlGaAs grown on vicinal (111)A GaAs by molecular beam epitaxy

Abstract

The photoluminescence spectra of single quantum well (SQW) structures grown on (111)A GaAs misoriented 3° towards the [100] direction are red shifted and broadened. These spectra also have extra peaks on the high-energy side, and the surface of the SQWs show giant steps towards [110] and [101] direction. Cross-sectional transmission electron microscopy of the SQWs on the 3°-misoriented (111)A surface clearly shows that the Al content is lower in the AlGaAs regions parallel to the (221)A or (331)A orientation and that the widths of GaAs wells increases at the risers of the giant steps towards [110] and [101]. On the exactly (111)A surfaces, the peak cathodoluminescence wavelength shows that the Al content on the AlGaAs triangle facets consisting of (221)A or (331)A planes is lower than on the flat surfaces. The AlGaAs layers grown on (111)A GaAs misoriented toward [011] have photoluminescence spectra whose intensity is stronger, and whose line width is narrower than the spectra from the AlGaAs layers grown on (111)A GaAs misoriented toward [100]. These phenomena are especially active for the AlGaAs grown on (111)A GaAs misoriented toward [110]. These novel lateral structures are most likely caused by the different sticking coefficients of Ga adatoms between on (111)A surfaces and (110) surfaces.