High-quality a-plane (11–20) GaN growth using double-lens structure on r-plane sapphire

•We have developed a double-lens structure (DLS) in a-plane GaN growth on r-plane sapphire substrate.•This structure consists of a HP-SiO2 mask on an a-plane GaN template grown on an HPSS.•DLS improved the crystal quality and light extraction efficiency in a-GaN template.

Growth of high-quality a-plane (11–20) GaN using a double-lens structure (DLS) on r-plane sapphire is reported. The DLS consisted of a hemispherically patterned SiO2 mask formed on an a-GaN template grown on a hemispherically patterned r-plane sapphire substrate. Our study suggests that the DLS was very effective in improving the crystal quality and optical properties in a-plane GaN growth on r-plane sapphire substrate owing to decreased defects and enhanced light extraction.