Fabrication and Characterization of Vertical Micro-Cavity Structures for GaN Surface Emitting Lasers(<Special Issue> Where are the Materials for Ultraviolet Devices and Where are These Going ?)

Abstract

We present the design and fabrication of highly reflective and low loss multilayer dielectric mirrors (SiO_2 /ZrO_2) for GaN based vertical cavity surface emitting lasers (VCSELs). We consider two types of VCSEL structures; one consists of AlN/GaN DBR and SiO_2/ZrO_2 DBR on a sapphire substrate. A resonant emission from a photo-pumped GalnN/GaN vertical cavity structure with a cavity length of 1.9pm has been demonstrated. The other consists of two dielectric mirrors (SiO_2/ZrO_2) with a polished thin sapphire substrate. A resonant emission from a photo-pumped GalnN/GalnN vertical cavity with a spectral line width of 3.8 nm has been demonstrated. Also, we propose a new structure using lateral growth on dielectric mirrors as a bottom reflector. We have demonstrated and characterized the thin GalnN/GaN 10 MQWs fabricated by removing a sapphire substrate with UV light irradiation for making a micro-cavity structure. The PL properties of standing-alone QWs show no noticeable degradation of QWs after the removing process. We pointed out the importance of the flatness of removed interfaces.