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HL: Fachverband Halbleiterphysik

HL 96: GaN: Growth and doping

HL 96.2: Vortrag

Freitag, 15. März 2013, 09:45–10:00, H15

Ordering phenomena in In_xGa_1−xN grown epitaxially on GaN(0001) — •Sangheon Lee, Christoph Freysoldt, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40627 Düsseldorf

The spatial distribution of In in In_xGa_1−xN epitaxial layers attract much attention, as In compositional fluctuations are often invoked to explain the realization of the high-efficiency blue light-emitting diodes (x ≃ 0.15) despite the large number of threading dislocations. However, the mechanisms determining the spatial distribution of In in the fully grown In_xGa_1−xN epitaxial layers are not well understood. We therefore developed an effective crystal growth modeling technique that combines a semi-grand-canonical Monte Carlo simulation with an ab-initio parameterized empirical force field. We elucidate local strain effects on the spatial distribution of In in coherent In_xGa_1−xN grown epitaxially on GaN(0001), with particular attention to the effect of the surface. In particular, we observe a strong tendency towards ordering in In_xGa_1−xN of x < 0.33, resulting in a stack of √3 ×√3 patterned InGaN monolayers. The effect of temperature on the ordering and thermodynamics is discussed, revealing that the ordering phenomena persists at real growth temperatures. The ordering phenomena are identified as a key factor that determines characteristic In compositional fluctuations in In_xGa_1−xN epitaxial layers with varying total indium contents.