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Article Dans Une Revue Journal of Crystal Growth Année : 2011

Wafer-scale selective area growth of GaN hexagonal prismatic nanostructures on c-sapphire substrate

Résumé

Selective area growth of GaN nanostructures has been performed on full 2" c-sapphire substrates using Si3N4 mask patterned by nanoimprint lithography (array of 400 nm diameter circular holes). A new process has been developed to improve the homogeneity of the nucleation selectivity of c-oriented hexagonal prismatic nanostructures at high temperature (1040 °C). It consists of an initial GaN nucleation step at 950 °C followed by ammonia annealing before high temperature growth. Structural analyses show that GaN nanostructures are grown in epitaxy with c-sapphire with lateral overgrowths on the mask. Strain and dislocations are observed at the interface due to the large GaN/sapphire lattice mismatch in contrast with the high quality of the relaxed crystals in the lateral overgrowth area. A cathodoluminescence study as a function of the GaN nanostructure size confirms these observations: the lateral overgrowth of GaN nanostructures has a low defect density and exhibits a stronger near band edge (NBE) emission than the crystal in direct epitaxy with sapphire. The shift of the NBE positions versus nanostructure size can be mainly attributed to a combination of compressive strain and silicon doping coming from surface mask diffusion.
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Dates et versions

hal-00601926 , version 1 (21-06-2011)

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Xiao Jun Chen, Jun-Seok Hwang, Guillaume Perillat-Merceroz, Stefan Landis, Brigitte Martin, et al.. Wafer-scale selective area growth of GaN hexagonal prismatic nanostructures on c-sapphire substrate. Journal of Crystal Growth, 2011, 322 (1), pp.15. ⟨10.1016/j.jcrysgro.2011.03.007⟩. ⟨hal-00601926⟩
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