Photoluminescence study of self-assembled GaAs quantum wires on (631)A-oriented GaAs substrates

The authors report a low-temperature photoluminescence (PL) study of multiple GaAs layers grown between AlAs(0.6 nm)/GaAs(0.6 nm) short-period superlattice barriers (SLBs) simultaneously grown on both GaAs(631) A and (100) substrates. Five GaAs-layers of different nominal thicknesses (L-W, ranging from 12 to 2.4 nm) were grown by molecular beam epitaxy. By using (631) A-oriented substrates a self-organized and highly ordered corrugation is obtained in the growth of the GaAs layers, and at the end of the SLB growth, flat surfaces are found. Whereas, for the (100)-oriented sample, flat interfaces are confirmed after the growth of GaAs and SLB layers. By reducing L-W below similar to 3.6 nm in the (631) sample, strong quantum wire (QWR)-like confinement is achieved as deduced from polarized PL spectroscopy where polarization degrees as large as 0.43 are obtained. The PL emission energy of the (631)-QWRs is redshifted, as compared with the transitions of the (100)-oriented quantum wells, when L-W is reduced. The authors explain this energy shift by the widening of the effective thickness of the confinement regions in the GaAs layers. (C) 2012 American Vacuum Society. [DOI:10.1116/1.3673798]