Characterization of nonpolar a-plane InGaN/GaN multiple quantum well using double nanopillar SiO_2 mask

摘要

The characteristics of nonpolar a-plane (1120) GaN (a-GaN) grown using single and double nanopillar SiO_2 masks were investigated. The two nanopillar SiO_2 masks were directly fabricated on an r-plane sapphire substrate and a-GaN by the epitaxial lateral overgrowth (ELOG) technique. Through the use of the single and double nanopillar SiO_2 masks, the crystalline quality and optical properties of a-GaN were markedly improved because of the nanoscale ELOG effect and a number of voids in the single and double nanopillar SiO_2 mask areas in comparison with the planar sample. The submicron pit densities of the planar, single, and double nanopillar mask samples were ～2 × 10~9,～7 × 10~8, and ～4 × 10~8cm~(-2), respectively. The internal quantum efficiency (IQE) values at room temperature of three-period InGaN/GaN multiple quantum wells (MQWs) grown using the planar, single, and double nanopillar masks were 45, 60, and 68% at a carrier concentration of 1.0 × 10~(18)cm~(-3), respectively.