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HL: Fachverband Halbleiterphysik
HL 58: Nitrides: Preparation and characterization I
HL 58.6: Vortrag
Donnerstag, 19. März 2020, 11:15–11:30, POT 112
Investigations on the defect luminescence in high aluminum containing AlGaN heterostructures — •Marcel Schilling, Norman Susilo, Tim Wernicke, and Michael Kneissl — Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstraße 36, 10623 Berlin, Germany
The realization of deep ultraviolet light emitting diodes (DUV-LEDs) with emission wavelength near 232 nm is very challenging as the photon energy is very close to the band gap of AlN, i.e. AlGaN layers with extremley high Al mole fraction are required. One problem is, that during metal organic vapor phase epitaxy of AlGaN crystalline point defects like vacancies or impurities are incorporated. Deep levels in the energy band gap associated to these point defects result in non-radiative carrier recombination decreasing the internal quantum efficiency (IQE) of DUV-LEDs. Therefore the understanding of the generation of point defects during the growth in high aluminum containing AlGaN layers is crucial for the development of efficient DUV-LEDs. In this study the defect luminescence of AlGaN layers is investigated by photoluminescence spectroscopy. The origin of the defect luminescence is determined by comparing defect luminescence spectra with transition energies for different defects and defect complexes reported in literature. Furthermore, the AlGaN layer quality is improved by optimizing the growth conditions in the reactor in correlation with the purity of the photoluminescence spectra. For example the defect luminescence in a 72% AlGaN layer near a wavelength of 442 nm, is investigated and most probably assigned to a VAl3− vacancy.