ENHANCED GAN DECOMPOSITION IN H-2 NEAR ATMOSPHERIC PRESSURES

GaN decomposition is studied at metallorganic vapor phase epitaxy pres sures (i.e., 10-700 Torr) in flowing H-2. For temperatures ranging fro m 850 to 1050 degrees C, the GaN decomposition rate is accelerated whe n the H-2 pressure is increased above 100 Torr. The Ga desorption rate is found to be independent of pressure, and therefore, does not accou nt for the enhanced GaN decomposition rate. Instead, the excess Ga fro m the decomposed GaN forms droplets on the surface which, for identica l annealing conditions, increase in size as the pressure is increased. Possible connections between the enhanced GaN decomposition rate, the coarsening of the nucleation layer during the ramp to high temperatur e, and increased GaN grain size at high temperature are discussed. [S0 003-6951(98)03540-2].