Effect of trench structure on the quality of InGaAs layers grown on patterned GaAs (1 1 1) A substrates

High-quality InGaAs layers were successfully grown on patterned GaAs (1 1 1 ) A substrates masked with SiNx film. It was found that a trench depth grea ter than or equal to 55 mu m was required to grow a InGaAs bridge layer ove r the trench. However, the InGaAs also grew from the trench bottom, which j oined the central part of the bridge layer. Consequently, the quality of th e bridge layer was degraded. The growth of InGaAs from the trench bottom wa s suppressed by depositing a SiNx film on the trench bottom, and as a resul t InGaAs layer formed a clean bridge over the trench. A low etch pit densit y and highly intense with sharp FWHM photoluminescence spectra obtained for bridge layers confirmed their high quality. (C) 1999 Elsevier Science B.V. All rights reserved.