CONTROL AND CHARACTERIZATION OF ORDERING IN GAINP

Ga0.51In0.49P layers have been grown by organometallic vapor phase epitaxy on GaAs substrates with [110]-oriented grooves on the surface that have an important effect on the formation of Cu-Pt ordered structures during growth. In this work, the groove shape is demonstrated to be critically important. For the optimum groove shape, single domains of the (111BAR) and (111BAR) variants of the Cu-Pt ordered structure are formed''on the two sides of the groove. Shallow grooves produce large domains on each side of the groove containing small domains of the other variant. For deep grooves, only a single variant is formed on each side of the groove, but the domains are small. For substrates with deep grooves on a GaAs substrate misoriented by 9-degrees, every groove contains large regions of highly ordered and completely disordered material separated by a few micrometers. This allows a direct determination of the effect of ordering on the band gap of the material using cathodoluminescence spectroscopy, allowing the first direct demonstration that ordering reduces the energy band gap of a III/V alloy.