Figure 1: XRD intensity profile through the 1-103wz and 113zb reflections for the samples grown on a 4° miscut substrate at 875°C and a V/III-ratio of 76 (a), and 1200 (b).

Figure 4: Feature sizes in (a) [110] and (b) [1-10] directions extracted from 2D-FFT of AFM height data of zb-GaN epilayers grown at different growth temperatures and a constant V/III-ratio of 76. (c) Variation of the aspect ratio of surface features with growth temperature. (d) Variation of root mean square surface roughness with growth temperature.

Figure 5: Zb-GaN content determined by XRD as a function of the GaN epilayer growth temperature.

Figure 8: Feature sizes in (a) [110] and (b) [1-10] directions extracted from 2D-FFT of AFM height data of the zb-GaN epilayers grown at different V/III-ratios and a constant growth temperature of 875 °C. (c) Variation of aspect ratio of surface features with V/III ratio. For (a) to (c), there are no data points for the sample grown at a V/III-ratio of 15, as it was not possible to extract feature sizes using the same 2D-FFT method as for other sample in the series. (d) Variation of root mean square surface roughness with V/III-ratio. The labels i, ii and iii indicate the proposed growth regimes.

Figure 11: Relative intensities of the zb-GaN XRD peaks for samples in the V/III-ratio series at a constant growth temperature of 875 °C.