Local band gap modulation of AlGaAs grown on patterned GaAs substrates

The growth of AlGaAs layers on patterned GaAs substrates by molecular-beam epitaxy is strongly determined by the interfacet surface migration of Ga adatoms, leading to a pronounced variation of the local Al concentration. Taking advantage of this migration process, we have overgrown mesa structures, that consist of intersecting stripes or partially overlapping squares, to obtain a local maximum or minimum, respectively, of the AlGaAs band gap on top of the mesas.