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HL: Fachverband Halbleiterphysik

HL 55: GaN: preparation and characterization II

HL 55.9: Vortrag

Freitag, 29. Februar 2008, 12:45–13:00, ER 164

Spatial distribution of structural defects in GaN — •I. Tischer¹, M. Schirra¹, M. Feneberg¹, G.M. Prinz¹, R. Sauer¹, K. Thonke¹, T. Wunderer², J. Hertkorn², F. Lipski², P. Brückner², F. Scholz², A. Chuvilin³, U. Kaiser³, I. Knoke⁴, and E. Meissner⁴ — ¹Institut für Halbleiterphysik, Universität Ulm — ²Institut für Optoelektronik, Universität Ulm — ³Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm — ⁴Abt. Kristallzüchtung, FHG-IISB, Erlangen

Non-polar and semi-polar GaN facets with reduced piezo-electric fields are promising substrates for high-efficiency optoelectronic devices. Due to the lower material quality compared to c-plane GaN these substrates typically show luminescence lines at 3.30 and 3.41 eV which are related to structural defects such as stacking faults. Here we study selectively overgrown triangular shaped GaN stripes with stable {1101} facets. They were purposely grown under non-optimal conditions so as to show the defect luminescence strongly.

Spatially resolved cathodoluminescence including monochromatic CL images and CL line scans of sample cross sections and of {1101} facets yield the intensity distribution of the 3.41 and 3.30 eV lines. Correlation of CL results with those from TEM support literature reports that the 3.41 eV line is related with basal plane stacking faults. The 3.30 eV defect is found to appear frequently in the close vicinity of the 3.41 eV defects but not exclusively there. Details of the spatial distribution together with CL measurements at varying temperatures towards the electronic nature of the defect will be discussed.