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HL: Fachverband Halbleiterphysik
HL 58: Nitrides: Preparation and characterization I
HL 58.9: Vortrag
Donnerstag, 19. März 2020, 12:00–12:15, POT 112
Effect of low temperature GaN underlayers on the carrier lifetimes in GaInN/GaN quantum wells — •Philipp Horenburg1, Philipp Henning1, Savutjan Sidik1, Uwe Rossow1, Heiko Bremers1,2, and Andreas Hangleiter1,2 — 1Institute of Applied Physics, Technische Universität Braunschweig, Germany — 2Laboratory for Emerging Nanometrology, Braunschweig, Germany
We demonstrate the impact of low temperature GaN underlayers (UL) grown under various conditions on the carrier lifetimes and the radiative efficiency and in GaInN/GaN quantum well (QW) structures. Since nonradiative recombination is associated with crystal defects in close proximity to the QW, the material grown underneath has a substantial influence on the carriers in QW. As the recombination dynamics can be significantly affected by changes in the density of defects and background carriers, the QW is not least susceptible to the growth conditions of this UL. We have grown a series of c-plane QW structures by low-pressure MOVPE on sapphire substrates. While GaInN is widely used an UL material, we chose a pure GaN UL grown at low temperature. Power and temperature dependent measurements show a strong increase of the internal quantum efficiency by two orders of magnitude compared to structures without a low temperature UL. Time-resolved photoluminescence measurements reveal that, with increasing thickness of the UL, not only the nonradiative lifetime increases, but also the radiative lifetime is affected just as for GaInN UL. These observations suggest that not the composition, but particularly the growth conditions affect the recombination dynamics in the QW structure.