Properties of GaN Epitaxial Layer Grown by MOVPE on MgAl₂O₄ Substrate

Abstract

We propose a MgAl₂O₄ substrate for GaN-based laser diodes. We grew GaN epitaxial layers using metal-organic vapor phase epitaxy on a MgAl₂O₄ substrate. The GaN on the MgAl₂O₄ showed a narrow X-ray diffraction peak of 310 arcsec, a photoluminescence dominated by the band-edge emission, and good electronic properties. The optical cavity was fabricated by cleaving the GaN on the MgAl₂O₄, and the stimulated emission from the cavity using optical pumping was observed. We also fabricated a light emitting diode (LED) with a AlGaN/InGaN double-heterostructure. The electroluminescence was dominated by the band-edge emission of InGaN with a narrow FWHM of 13.5 nm. The characteristics of LED on the MgAl₂O₄ were comparable to that on a A1₂O₃ substrate. MgAl₂O₄ is feasible as a substrate for laser applications.