Optically Pumped Lasing Action with Unusual Wavelength of Approximately 390 nm in Hexagonal GaN Microdisks Fabricated by Radio-Frequency Plasma-Assisted Molecular Beam Epitaxy

Abstract

Hexagonal GaN microdisks exhibiting lasing action with unusual wavelengths of approximately 390 nm under an optically pumped condition have been investigated. The lasing action was caused by the resonant modes of the whispering gallery mode and/or quasi-whispering gallery mode in the hexagonal microdisks. A cross-sectional transmission electron microscopy observation indicated that multiple crystalline boundaries, which are formed by stacking faults, were included in the specific GaN microdisks exhibiting such an unusual lasing action. The origin of the optical gain was discussed, based on the modification of the crystal structure associated with the stacking faults.