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HL: Fachverband Halbleiterphysik

HL 12: Group-III-Nitrides: Optical Properties I

HL 12.4: Vortrag

Montag, 22. März 2010, 14:45–15:00, H15

Impact of the AlN seeding layer thickness on GaN orientation on high index Si-substrates — •Roghaiyeh Ravash, Jürgen Bläsing, Peter Veit, Thomas Hempel, Armin Dadgar, Jürgen Christen, and Alois Krost — Otto-von-Guericke-University Magdeburg, FNW/IEP/AHE, Postfach 4120, 39016 Magdeburg, Germany

Silicon is considered to be a reasonable alternative to substrates such as sapphire and SiC, because of its low price and availability in large diameters. Because of spontaneous and strain induced piezoelectric polarization field along the c-axis, leading to the separation of electrons and holes in quantum wells reducing the recombination efficiency, c-axis oriented GaN-based light emitters have a low efficiency, especially in the longer wavelength region. In order to reduce or eliminate these polarization effects, semi-polar or non-polar GaN-heterostructure is favored. In this work we investigated the growth of GaN applying a low temperature AlN seeding layer with various thicknesses. The impact of the AlN seeding layer on GaN orientation using different Si substrate orientations (e. g. (211), (711), (410), (100)+4.5° off) were investigated by x-ray diffraction measurements in Bragg-Brentano geometry and x-ray pole figure measurements. We found that the thickness of the AlN seeding layer plays a significant role in obtaining different GaN textures. Applying a about 4 nm AlN seeding layer we achieved a single crystalline GaN epilayer on Si (211) with a 18 ° tilted c-axis orientation. Some of the samples were characterized by scanning electron microscopy and transmission electron microscopy.