Quantitative analysis of small amounts of cubic GaN phase in GaN films grown on sapphire

Abstract

Thin GaN films, grown by metal organic chemical vapor deposition on the basal plane of sapphire substrates, were characterized by x-ray pole figures, highresolution x-ray diffraction and transmission electron microscopy. This combination was found sensitive to small amounts (down to 0.1%) of cubic GaN phase in specimens subjected to surface nitridation treatment prior to epitaxial growth. The presence of the cubic phase and its orientation relations to the hexagonal GaN matrix was established by means of pole figures and selected area electron diffraction. The amount of cubic phase was determined by comparing the integrated x-ray diffraction intensities of the (311) cubic GaN and the (11.2) hexagonal GaN reflections. Optimum nitridation duration was found, which corresponds to almost complete suppression of the cubic phase formation.

Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal–organic chemical vapour deposition

“…Significantly, no threading dislocations were observed in the nanowires, although (0001) basal-plane stacking faults were commonly observed. (0001) stacking faults are known to have a low defect energy and are frequently observed in GaN films [29][30][31][32][33] and have also been reported in GaN nanowires [9,12,13,34]. Figure 6 [0001] GaN direction and ∼16% in the [ 1100] GaN direction.…”

MOCVD synthesis of group III-nitride heterostructure nanowires for solid-state lighting.

“…The structural characteristics of the aligned nanowires were investigated by transmission electron microscopy (TEM), which showed that the GaN nanowires have a single crystalline, wurtzite structure. The triangular sides of the [11][12][13][14][15][16][17][18][19][20] oriented nanowires were determined to consist of the (0001), (-1101), and (-110-1) planes, resulting in an isosceles cross-section. Significantly, no threading dislocations were observed in the nanowires, although (0001) basal-plane stacking faults were commonly observed.…”

“…Significantly, no threading dislocations were observed in the nanowires, although (0001) basal-plane stacking faults were commonly observed. (0001) stacking faults are known to have a low defect energy and are frequently observed in GaN films [9][10][11][12][13] and have also been reported in GaN nanowires.…”