Influence of the nucleation layer morphology and epilayer structure on the resistivity of GaN films grown on c-plane sapphire by MOCVD

Influence of sapphire annealing in trimethylgallium atmosphere on GaN epitaxy by MOCVD

“…The density of dislocations in sample #7 was about 1.3 Â 10 9 cm À2 . This value of defect density is comparable with GaN samples grown on sapphire by two-step growth method [22]-but it should be pointed out that the above-described processes were not optimized towards the reduction of dislocations. For sample #8 it was not possible to establish the density of defects after E+M etching, because N-polar material etches much faster then Ga-polar GaN [23].…”

Growth of Fe doped semi‐insulating GaN on sapphire and 4H‐SiC by MOCVD

“…Images of the etched samples and calculated values of pits density are presented in Figure 1 and in Table 1, respectively. It shows that Fe doping increases the TDs density which is in opposite to literature [8].The presence of Fe in the lattice may act in the same way as changing the nucleation layer structure, which induces different types of defects in the layer thereby increasing the resistivity [9]. Screw dislocations are electrically conductive [10], mixed dislocations are electrically inactive or not highly conductive [11][12][13], and edge dislocations work as a acceptor-like trap levels [14] or are negatively charged and not highly conductive [13].…”

Reduction of the dislocation density in HVPE-grown GaN epi-layers by an in situ SiNx treatment

“…One way of controlling the density of GaN nuclei in metal-organic chemical vapor deposition (MOCVD) technique is provided by the control of composition of the carrier gas [4,5]. The ex situ masking of substrates with dielectric materials in specific geometries that allows nucleation only on non-masked areas is also a suitable technique in this regard [6,7].…”