Defect reduction via confined epitaxial growth of GaN

This work focuses on better understanding confined epitaxy of GaN by metal organic chemical vapor deposition on patterned substrates including sapphire and SiC, both with and without GaN epilayers. Preliminary results show a marked improvement in dislocation density with decreasing feature size, as compared to growth in adjacent large areas (100¿m wide) on the same wafer. This improvement virtually disappears as feature diameters reach 20¿m. Along with the decrease in dislocation density, the confined epitaxy also exhibits a reduction in grain boundaries.