Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 61: GaN: Preparation and Characterization II (mainly structural)

HL 61.2: Vortrag

Mittwoch, 28. März 2012, 15:15–15:30, EW 202

Epitaxy and characterization of Al_1-xIn_xN grown by low pressure MOVPE on various substrates — •Ernst Ronald Buss, Uwe Rossow, Heiko Bremers, and Andreas Hangleiter — Institut für Angewandte Physik, TU Braunschweig

Due to the advantages of Al_1-xIn_xN compared to Al_xGa_1-xN regarding lattice mismatch and contrast in refractive index to GaN it is a very promising material for claddings in GaN based laser structures. To minimize optical losses the Al_1-xIn_xN layers have to be quite thick, of high crystalline quality and very smooth.

Lattice matched Al_1-xIn_xN grown by low pressure MOVPE exhibits a typical surface morphology for small layer thicknesses consisting of small features of about 100 nm in diameter, some of which are decorated with a pit inside. To investigate the influence of parameters like the strain state of the Al_1-xIn_xN, the defect density of the substrate, the material of the underlying layer, or the presence of (1101) facets on surface morphology we performed growth experiments of single layer samples and multi layer structures on various substrates and templates. It turned out that the surface of Al_1-xIn_xN gets more fine-grained with increasing layer thickness. Varying the material of the underlying layer we were able to initiate the fine-grained morphology for thinner layers. For very large layer thicknesses, as well as for stacked sample structures of Al_1-xIn_xN and GaN with a large total film thickness of Al_1-xIn_xN we can observe a splitting in the composition independent of the properties of the underlying material. Hence, the origin of this splitting must be an instability during growth.