Effect of growth temperature and V/III-ratio on the surface morphology of MOVPE-grown cubic zincblende GaN
Journal of Applied Physics
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Lee, L. Y., Frentrup, M., Kappers, M., Oliver, R., Humphreys, C., & Wallis, D. (2018). Effect of growth temperature and V/III-ratio on the surface morphology of MOVPE-grown cubic zincblende GaN. Journal of Applied Physics, 124 (10)https://doi.org/10.1063/1.5046801
The influence of growth temperature and V/III-ratio on the surface morphology of (001) cubic zincblende GaN epilayers during metal organic vapour phase epitaxy (MOVPE) growth has been investigated using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The zincblende phase purity as determined by X-ray diffraction (XRD) was found to be above 98 % for most GaN epilayers studied. As the growth temperature was increased from 850 °C to 910 °C, and as the V/III-ratio was separately increased from 38 to 300, surface features were found to be elongated in [1-10] direction, and the ratio of the length to width of such surface features was found to increase. Faceting was observed at V/III-ratios below 38 and above 300, which in the latter case was accompanied by a reduction of the zincblende phase purity. An explanation for these morphological trends is proposed based on effects such as the reduced symmetry of the top monolayer of the (001)-oriented zincblende GaN lattice, diffusion of Ga and N adatoms on such a surface, and the relative energies of the crystal facets.
We would like to thank Innovate UK for the financial support within the Energy Catalyst Round 2 - Early Stage Feasibility scheme (Ref. 132135) and Energy Catalyst Round 4 - Mid Stage Feasibility scheme (Ref. 102766). We acknowledge the support of EPSRC through grant no. EP/M010589/1 and grant no. EP/R01146X/1. DJW would like to thank the support of EPSRC through grant no. EP/N01202X/1.
Technology Strategy Board (TS/N003756/1 - 132135)
EPSRC (via Cardiff University) (513956)
External DOI: https://doi.org/10.1063/1.5046801
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285120