Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.27: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Systematic study of C- and M-plane growth of GaN on LiAlO₂ by plasma assisted MBE — •Ralf Schuber¹, Yen-Liang Chen², Yu-Chi Hsu², and Daniel M. Schaadt¹ — ¹Institut für Angewandte Physik, Universität Karlsruhe (TH) and DFG Center for Functional Nanostructures, CFN, D-76128 Karlsruhe — ²Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC

Group III nitrides grown along the <0001> direction show a strong quantum confined Stark effect due to the electric fields resulting from the spontaneous and piezoelectric polarization. These fields cause a reduction of the oscillator strength due to a spatial separation of electrons and holes and a decrease in the energy of the radiative transition. Epitaxial layers with non-polar surfaces such as the M-plane {1100} are attractive due to the absence of built-in electrical fields. LiAlO₂ constitutes a particularly suitable substrate as its lattice mismatch to both C- and M-plane oriented GaN lies below 2%. While molecular beam epitaxy growth of M-plane films on LiAlO₂ has been well established, the growth of C-plane nitrides on LiAlO₂ is poorly understood. To investigate the transition from M-plane to C-plane growth, we have studied the impact of various growth parameters, such as the Ga to N flux ratio, the nucleation and epi layer temperature and thickness. It was found that the crystal orientation of GaN can be adjusted by selecting appropriate growth conditions.