OMVPE growth and gas-phase reactions of AlGaN for UV emitters

Gas-phase parasitic reactions among TMG, TMA, and NH3, are investigated by monitoring the growth rate/incorporation efficiency of GaN and AlN using an in situ optical reflectometer. It is suggested that gas phase adduct (TMA: NH3) reactions not only reduce the incorporation efficiency of TMA but also affect the incorporation behavior of TMGa. The observed phenomena can be explained by either a synergistic gas-phase scavenging effect or a surface site-blocking effect. Relatively low reactor pressures (30-50 Torr) are employed to grow an AlGaN/GaN QW p-n diode structure. The UV emission at 354 nm (FWHM similar to 6 nm) represents the first report of LED operation from an indium-free GaN QW diode. (C) 1998 Published by Elsevier Science B.V. All rights reserved.