Hydride vapour phase epitaxy growth of GaN layers under reduced reactor pressure

In this paper, Hydride Vapour Phase Epitaxy (HVPE) of GaN layers under redu ced pressures is reported. First results show that the HVPE grown GaN layer s exhibit excellent electrical, crystallographic and optical quality. By re ducing the reactor pressure from 950 to 250 mbar, improvements in backgroun d doping (down to 2 x 10(16) cm(-3)) and Hall mobility (up to 300 cm(2)/Vs) are observed. Experiments on MOVPE overgrowth on HVPE GaN layers show exce llent results. Low temperature PL spectra of the overgrowth MOVPE layer rev eal all three free exciton levels (FE A, FE B, FE C) without any visible bo und excitons.