Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 55: GaN: preparation and characterization II

HL 55.6: Vortrag

Freitag, 29. Februar 2008, 11:45–12:00, ER 164

Impact of seed and buffer layer growth on the quality of AlGaN on Si(111) — •P. Saengkaew, A. Diez, M. Noltermeyer, J. Blaesing, B. Bastek, F. Bertram, A. Dadgar, J. Christen, and A. Krost — Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106, Magdeburg, Germany

AlGaN with its bandgap ranging from 3.4 to 6.3 eV, is a very attractive material to fabricate UV photodetectors and UV LEDs. For efficient devices, high-quality AlGaN films are required. Growing high-quality AlGaN grown on Si (111) by MOVPE, the lattice mismatch and different thermal expansion of them have to be overcome. Not only the growth parameters of AlGaN but also the seeding and buffer layers play an important role to improve the quality of AlGaN grown on them. Conventionally AlN layers are employed as a seeding layer to grow Al0.1Ga0.9N on Si. We investigated the impact of the growth seeding parameters as growth temperature, pressure, time, and V/III ratio of the AlN seeding and buffer layers on the crystalline quality and strain state of AlGaN by high-resolution X ray diffraction, AFM, and CL .Best values achieved for the simple AlN / AlGaN structure are 0.33 degree and 0.55 degree for the (0002) and (10-10) omega scans, respectively. A further improvement can be achieved by introducing an AlN based superlattice between the seeding and AlGaN buffer layer. For the best structure we achieve values for the (0002) and (10-10) omega scans of 0.15 degree and 0.39 degree, respectively.