Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 72: Focus Session: Extended defects in semi- and nonpolar GaN I
HL 72.2: Topical Talk
Donnerstag, 14. März 2013, 10:00–10:30, H13
Identification of defects in semipolar GaN and (Al,Ga,In)N by cathodoluminescence spectroscopy — •Klaus Thonke1, Ingo Tischer1, Matthias Hocker1, Manuel Frey1, and Ferdinand Scholz2 — 1Institute of Quantum Matter / Semiconductor Physics Group, Ulm University, 89081 Ulm, Germany — 2Institute of Optoelectronics, Ulm University, 89081 Ulm, Germany
The growth of nitride semiconductor layers on semipolar planes typically introduces specific crystalline defects in relatively high concentrations. These defects create local strain, deteriorate the electrical properties, and act as nonradiative recombination centers. Mainly basal plane stacking faults of I1 and I2 type are introduced, terminated eventually by prismatic stacking defects or dislocations. To correlate specific types of defects with the commonly observed multiple mostly broad sub-bandgap luminescence emission bands, optical methods with very high spatial resolution in the range of few 10 nm are required. Here, either transmission electron microscope (TEM) or low-energy scanning electron microscope (SEM) based cathodoluminescence (CL) setups yield valuable information. By spatial correlation of CL maps with high-resolution TEM micrographs recorded on exactly the same sample cross section, direct correlation can be obtained. These defects also affect the incorporation of dopant atoms like Mg, or of In and Al atoms when quantum well structures are grown. We discuss the most prominent cases, and look also into the characteristic shift of the emission bands with changes in the (Al,Ga,In) composition.