The growth mechanism of GaN with different H2/N2 carrier gas ratios

Investigation of MOCVD growth parameters on the quality of GaN epitaxial layers

“…Therefore the high R s was probably due to the increase in acceptor-like centers introduced by edge segments of TDs as reported by other groups [9], not by the reduction of background doping by oxygen or other impurities that were more easily trapped during the early stage of GaN growth (nucleation and pre-recovery) due to the high density of defects and resulted dangling bonds. This type of unintentional doping can be reduced by the reduction of coalescence time as reported by other groups [3,10], as well as our previously unpublished results regarding un-doped GaN studies. …”

“…On the other hand, Steins et al [2] obtained better growth uniformity using N 2 carrier gas. In addition, the effect of N 2 and H 2 as carrier gas on the coalescence (recovery) time of GaN nucleation islands was studied by Cho et al [3]. Due to the high temperatures and resulting complex gas-phase and surface reactions that occur in MOCVD epitaxy of GaN [4,5], choosing proper gas ratios for the main hydride mixtures at a suitable growth temperature is not straightforward.…”

Influence of growth temperature on GaN:Cr incorporation and structural properties in MOVPE

“…Trimethylgallium (TMGa), ammonia (NH 3 ), and bis(cyclopentadienyl)chromium (Cp 2 Cr) were used as Ga, N, and Cr precursors, respectively. A 25-nm-thick low temperature GaN nucleation layer was grown at 550 1C in H 2 environment followed by a 1.5-mm-thick undoped GaN buffer layer using our optimized growth conditions [20][21][22]. Subsequently an about 500-nm-thick GaN:Cr layer was deposited at different temperatures (900-1125 1C).…”

Effect of growth pressure on coalescence thickness and crystal quality of GaN deposited on 4H–SiC

“…The GaN deposition mechanism was first described by Hiramatsu et al [1], and it was also investigated by others [2,3]. The influence of reactor pressure on the morphology of GaN deposited on a sapphire was studied by Wickenden et al [4].…”

“…The process of coalescence could be characterized as well by the duration of the process and the thickness of the layer immediately after fusion. These parameters, which can be used interchangeably, are very important from the point of view of the structural quality of the GaN layer [3].…”