Visible resonant modes in GaN-based photonic crystal membrane cavities

Abstract

Photonic crystal membrane cavities play a key role as building blocks in the realization of several applications, including quantum information and photonic circuits. Thus far, there has been no work on defect cavities with active layers emitting in the UV to green range of the spectrum based on the (Al,In,Ga)N material system. While this material system has great potential for a new generation of optoelectronic devices, there are several obstacles for the fabrication of GaN-based membrane cavities, including the absence of a conventional selective chemical wet etch. Here, we demonstrate the first fabrication of fully undercut GaN photonic crystal membranes containing an InGaN multiquantum well layer, fabricated using band-gap-selective photoelectrochemical etching. A postfabrication coating of Ta2O5 is used to tune the cavity modes into resonance with the quantum well emission, and the fabricated membranes exhibit resonant modes with Q=300.