MBE growth of different hexagonal GaN crystal structures on vicinal (100) GaAs substrates

GaN thin films of different hexagonal crystal structures have been grown by radio-frequency nitrogen plasma source molecular beam epitaxy (RFMBE) on v icinal (100) GaAs substrates. Polycrystalline hexagonal material occurred f or high temperature (630 degreesC) nitridation of the GaAs surface or low t emperatures of the initial GaN buffer layer deposition. On the contrary, in itial GaN growth at 540 degreesC gave hexagonal single crystals with [0001] axis either inclined at approximately 43 degrees from the growth axis or a ligned parallel to it. The GaN orientation depended on the annealing or not , respectively, of the initial low temperature buffer layer. (C) 2001 Elsev ier Science B.V. All rights reserved.