Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 17: Nitrides: Growth and Characterization
HL 17.3: Vortrag
Montag, 14. März 2011, 15:00–15:15, POT 51
Raman spectroscopic investigations on epitaxial grown GaN on sapphire — •Christian Röder1, Cameliu Himcinschi1, Jens Kortus1, Frank Habel2, and Gunnar Leibiger2 — 1TU Bergakademie Freiberg, Institute for Theoretical Physics, Leipziger Str. 23, D-09596 Freiberg — 2Freiberger Compound Materials GmbH, Am Junger-Löwe-Schacht 5, D-09599 Freiberg
One of the biggest challenges of GaN layer preparation is the lack of cost-efficient and high-quality substrates for homoepitaxy. In order to optimize the growth conditions and to understand relaxation mechanisms we investigated a series of heteroepitaxial grown GaN layers on sapphire differing in their layer thickness. By means of confocal Raman spectroscopy we obtained depth spatial information. Analyzing the position of the E2(high) phonon mode we found a wavenumber shift within all layers. This indicates a stress relaxation from the interface to the top of the layer. Furthermore we observed a decreasing compressive stress with increasing layer thickness. Assuming a planar stress state the determined shifts were converted to stress values. These results were compared with simulations using a model of wafer curvature. Additionally the shift of the E2(high) mode was correlated with results of photoluminescence (PL) measurements performed at 293 K. The changes of the band gap derived from the PL data were in excellent agreement compared with the strain dependent band structure at the Γ point. The authors would like to thank the European Union (EFRE) as well as the Free State of Saxony for financial support within the ADDE project.