MOLECULAR-BEAM EPITAXY GROWTH AND PROPERTIES OF GAN, INGAN, AND GAN INGAN QUANTUM-WELL STRUCTURES/

Growth of m-V nitrides by molecular beam epitaxy (MBE) was studied usi ng rf nitrogen plasma sources. Plasma sources from three different ven dors have been tested. All three of the sources have been used to grow high quality GaN. However, the EPI rf source produces an optical emis sion spectrum that is very rich in the active nitrogen species of Ist- positive excited nitrogen molecules and nitrogen atoms. GaN growth rat es at 800 degrees C of 1 mu m/h have been achieved using this source. The MBE-grown GaN films are deposited homoepitaxially on high quality metalorganic vapor phase epitaxy-grown GaN/SiC substrates. With the gr owth conditions for high quality undoped GaN as a base line, a detaile d study of Mg doping for p-type GaN was performed. An acceptor incorpo ration of 2 x 10(19) cm(-3) was measured by both capacitance-voltage a nd secondary ion mass spectroscopy for a doping source temperature of 290 degrees C. However, a faceted three-dimensional growth mode was ob served by reflection high energy electron diffraction during Mg doping of GaN. Additional studies suggest an interdependence between Mg inco rporation and growth surface morphology. Quantum well structures made from the InGaN ternary alloy were grown using a modulated beam MBE met hod. With this technique, quantum well compositions were controllable, grown with visible luminescence ranging from 400 to 515 nm depending on indium mole fraction. Light emitting diode test structures, combini ng Mg p-type doping with InGaN quantum wells, were fabricated and test ed. (C) 1998 American Vacuum Society.