Gain and photoluminescence spectroscopy in violet and ultraviolet InAlGaN laser structures

Abstract

We report on gain and photoluminescence spectroscopy on optically pumped violet and ultraviolet InGaN and InAlGaN multi quantum well laser structures grown on sapphire substrates by metalorganic chemical vapor deposition. Gain spectroscopy was used to study the optical gain and loss mechanisms in these structures. We demonstrate optically pumped InAlGaN laser diodes at 343 nm with lasing threshold at an excitation power of 0.7 MW/cm2. Sub-bandgap absorption in Mg-doped waveguide layers and absorption of leakage modes in the underlying GaN buffer layer are identified as major loss mechanism. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)