Origin of faceted surface hillocks on semi-polar ð1 1 2 2Þ GaN templates grown on pre-structured sapphire
Journal of Crystal Growth
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Han, Y., Caliebe, M., Kappers, M., Scholz, F., Pristovsek, M., & Humphreys, C. (2015). Origin of faceted surface hillocks on semi-polar ð1 1 2 2Þ GaN templates grown on pre-structured sapphire. Journal of Crystal Growth, 415 170-175. https://doi.org/10.1016/j.jcrysgro.2014.12.040
The microstructure of semi-polar (1 1 2 2) GaN templates grown on pre-structured r-plane sapphire by metal–organic vapor phase epitaxy (MOVPE) followed by hydride vapor phase epitaxy (HVPE) has been characterised by transmission electron microscopy (TEM). It is found that dislocations originating from the inclined c-plane-like GaN/sapphire interface bend and then terminate either at the coalescence regions of the adjacent GaN stripes or at the SiO2 mask. However, the regions associated with the coalescence event during the MOVPE growth act as a source of dislocations and stacking faults in the subsequent growth process. More importantly, a direct link between the formation of a surface hillock, the presence of an inversion domain, and the preferential nucleation of randomly oriented GaN particles at a region containing a dislocation bundle originating from coalescence has been established. It is suggested that controlling the surface conditions of the MOVPE GaN layer before HVPE and optimising the HVPE nucleation process are important to avoid the surface hillocks.
Characterization, Defects, Hydride vapor phase epitaxy, Metalorganic vapor phase epitaxy, Nitrides, Semiconducting III–V materials
This work was financially supported by the European Commission (FP7) within the framework of the project “AlGaInN materials on semi-polar templates for yellow emission in solid state lighting applications” (ALIGHT) (Project no.: 280587) and by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the project “Polarization Field Control in Nitride Light Emitters” (PolarCoN).
External DOI: https://doi.org/10.1016/j.jcrysgro.2014.12.040
This record's URL: https://www.repository.cam.ac.uk/handle/1810/247165