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 SiN_x film. It was found that a trench depth 55 μm was required to grow a InGaAs bridge layer over the trench. However, the InGaAs also grew from the trench bottom, which joined the central part of the bridge layer. Consequently, the quality of the bridge layer was degraded. The growth of InGaAs from the trench bottom was suppressed by depositing a SiN_x film on the trench bottom, and as a result InGaAs layer formed a clean bridge over the trench. A low etch pit density and highly intense with sharp FWHM photoluminescence spectra obtained for bridge layers confirmed their high quality.