Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 31: Poster: Nitrides
HL 31.12: Poster
Montag, 31. März 2014, 17:00–20:00, P2
Analysis of semipolar gallium nitride layers by µ-Raman spectroscopy — •Lisa Hiller1, Philipp Schustek1, Matthias Hocker1, Sebastian Bauer1, Marian Caliebe2, Tobias Meisch2, 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
In recent years, great efforts have been undertaken to explore semipolar gallium nitride (GaN) layers, which are predicted to reduce significantly the built-in electric fields. We investigate thick semipolar (1122)-oriented GaN layers grown on pre-structured sapphire by a sequence of metalorganic vapour phase epitaxy and hydride vapour phase epitaxy.
Confocal Raman spectroscopy with micron-scale resolution gives access to bulk information by non-destructive depth resolved scanning of the sample. The strain analysis on the basis of Raman tensor elements provides a tool of determining local strain fields, which we compare to finite element based simulations. It allows us to characterize different structural domains resulting from the two different growth processes. Furthermore, uncontrolled high dopant concentrations could be identified by the observation of coupled phonon-plasmon modes. Spatially and spectrally resolved cathodoluminescence and secondary ion mass spectrometry confirm these findings.