Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 13: Nitrides: Optical characterization
HL 13.5: Talk
Monday, March 31, 2014, 12:15–12:30, POT 251
Micro-photoluminescence and micro-Raman studies on strained polar GaN layers — •Sebastian Bauer1, Matthias Hocker1, Lisa Hiller1, Frank Lipski2, Ferdinand Scholz2, and Klaus Thonke1 — 1Institute of Quantum Matter / Semiconductor Physics Group, Ulm University, 89081 Ulm, Germany — 2Institute of Optoelectronics, Ulm University, 89081 Ulm, Germany
Heteroepitaxial growth of c-oriented gallium nitride (GaN) layers by hydride vapor phase epitaxy (HVPE) on sapphire substrates is always associated with specific strain states in the grown material. The efficiency of optoelectronic devices suffers from strain-induced piezoelectric effects as well as from structural defects caused by strain. Hence, the mechanism of strain relaxation with increasing layer thickness is of great interest.
We investigate a series of samples with different thicknesses grown by HVPE by spatially resolved low temperature microphotoluminescence and room temperature micro-Raman spectroscopy. The correlation between the layer thickness and the strain state of the material is analysed. These results suggest a minimum substrate layer thickness of GaN required for the realization of strain-free device material.