Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 16: III-V semiconductors II

HL 16.7: Talk

Tuesday, March 24, 2009, 11:15–11:30, POT 151

Optimization of AlN-based seeding and superlattice buffer layers to grow high-quality AlxGa1-xN with Al content up to x=0.66 on Si (111) substrates — •P. Saengkaew, A. Dadgar, J. Blaesing, B. Bastek, F. Bertram, T. Hempel, P. Veit, J. Christen, and A. Krost — AHE/IEP/FNW,Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

AlxGa1-xN is one of the most attractive materials to develop UV optoelectronic devices due to its direct wide-bandgap energy from 3.4 to 6.2 eV. Here we present MOVPE-grown high-quality AlxGa1-xN layers with Al content up to x=0.66 on Si (111) substrates. With optimized AlN-based seeding and superlattice buffer, crack-free layers with smooth surface and low defect density were obtained. Initially, the impact of the AlN seeding layer was investigated by varying growth parameters as growth temperature, time, pressure and V/III ratio. To optimize high- and low-temperature AlN-based superlattices, the growth temperature, growth time, and number of SL periods were varied. These optimized AlN seeding and SL layers are efficient in reducing the dislocation density and in-plane strain. By HR-XRD, the crystalline quality of AlxGa1-xN was characterized. The finite thickness fringes of AlxGa1-xN have been observed in theta/2theta-scans of the (0002) reflections showing their excellent crystalline quality and abrupt smooth surface. AFM and FE-SEM measurements were used to observe the surface morphology and TEM measurements to determine the dislocation behaviour. The optical properties were investigated by CL measurements.