Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 72: Focus Session: Extended defects in semi- and nonpolar GaN I

HL 72.9: Talk

Thursday, March 14, 2013, 13:00–13:15, H13

Epitaxy of Al_1-xIn_xN on different GaN-surface orientations — •Ernst Ronald Buß, Uwe Rossow, Heiko Bremers, and Andreas Hangleiter — Institute of Applied Physics, TU Braunschweig

Al_(1-x)In_xN with thicknesses exceeding 250 nm deposited on c-plane oriented GaN exhibits a distinct splitting of the composition and a very strong roughening of the surface. An increase in indium incorporation efficiency of Al_(1-x)In_xN on the (112l) side facets (l=1,2,3) of the V-pits, compared to c-plane orientation, has been frequently mentioned in the literature to be the origin of the composition splitting and strong roughening. To clarify possible dependencies Al_(1-x)In_xN layers grown on differently oriented GaN substrates and templates, with various thicknesses have been investigated regarding surface morphology, composition splitting and orientation of the V-pits. It became apparent that the growth rates, as well as the incorporation efficiency of Al_(1-x)In_xN are comparable for the polar (0001), and the non polar (1100) surfaces. On semi-polar (1122) surface Al_(1-x)In_xN incorporates indium more efficiently as compared with (0001) and (1100) surfaces. Al_(1-x)In_xN grown on pitted GaN with typical (1101) side facets does not reveal an additional composition on this semi-polar surface orientation. The formation of differently oriented V-pits in the Al_(1-x)In_xN, compared with the V-pits in other group III-nitrides, is the key to understand the seemingly intrinsic behavior of composition splitting of Al_(1-x)In_xN. These results are in perfect agreement with investigations of higher indium content inside the pits formed during growth of Al_(1-x)In_xN with (112l) side facets in the literature.