High quality nitride based microdisks obtained via selective wet etching of AlInN sacrificial layers

Abstract

The authors report a technique for selective wet chemical etching of an AlInN sacrificial layer lattice-matched to GaN for the fabrication of air-gap photonic structures. It is used to demonstrate high quality factor (Q) microdisk cavities. Whispering gallery modes are observed in the photoluminescence spectra of InGaN∕GaN quantum wells (QWs) embedded in the GaN microdisks. Q factors of up to 3500 are obtained. The measured Qs are found to be limited by the QW absorption. Room temperature laser action is achieved for a wide spectral range (409–475nm) with a threshold down to 166kW∕cm2.