Selective area growth and epitaxial lateral overgrowth of GaN by metalorganic vapor phase epitaxy and hydride vapor phase epitaxy

Abstract

Recent results on the selective area growth (SAG) and epitaxial lateral overgrowth (ELO) of GaN via metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HYPE) are reported. GaN sub-micron dots have been fabricated successfully via MOVPE-SAG on dot-patterned GaN (0001) epitaxial layer/sapphire substrate and also on dot-patterned sapphire substrate using AlN low temperature (LT) buffer layer. The smooth surface is obtained via MOVPE-ELO for both the 〈11 2 ̄ 0〉 and 〈1 1 ̄ 00〉 sub-micron SiO 2 stripes. The reduction in dislocation density is confirmed by using TEM. Furthermore, the HVPE-ELO of GaN is performed on two mask patterns with the 〈11 2 ̄ 0〉 and 〈1 1 ̄ 00〉 stripes. In the 〈11 2 ̄ 0〉 stripe the ELO layer surface is not uniform, covered with {1 1 ̄ 01} facets in which the growth rate is very slow. On the other hand, in the〈1 1 ̄ 00〉 stripe the surface of the ELO layer becomes uniform with (0001) face. The defect structures of the ELO layers are characterized by a growth pit density (GPD) using a thin InGaN epitaxial layer grown on the ELO GaN layer and a cathodoluminescence (CL). It is found that the defect structures are strongly related to the growth mechanism during the ELO process.