Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 16: III-V semiconductors II

HL 16.2: Vortrag

Dienstag, 24. März 2009, 09:45–10:00, POT 151

Temperature and Time Resolved Measurements of Nitride-based Quantumwell Structures on Modified GaN Substrates — •Miran Alic¹, Christian Nenstiel¹, Ronny Kirste¹, Markus R.Wagner¹, Axel Hoffmann¹, Tadek Suski², Martin Albrecht³, and Tobias Schulz³ — ¹Technische Universität zu Berlin Institut für Festkörperphysik — ²Institute of High Pressure Physics "Unipress" Warsaw — ³Leibniz-Institut für Kristallzüchtung Berlin

Over the last few years InGaN-based semiconductors attracted much attention, especially in the domain of light emitting device applications. We report on temperature-dependent time-integrated and time-resolved photoluminescence studies of InGaN/GaN multi quantum wells (MQWs) grown by hydride vapor phase epitaxy. MQW structures composed of 3 InGaN QWs were grown on a GaN substrate with an intended variation of the misorientation angle with respect to the c-axis, as well as a different degree of indium content. The samples exhibit a broad peak around a central wavelength of 2.92eV (5K). Temperature resolved PL measurements for this peak display a redshift without a characteristic "S-shape" behavior in the range of 0 - 300K. A "S-shape" would indicate an energy transfer mechanism from lower energy levels to higher energy states through the energy barrier. However, the absence of this behavior suggests the barrier to be higher than 27meV. Time resolved measurements at different energies between 2.88eV and 3.02eV revealed a constantly decreasing carrier lifetime. We assume that this behavior is attributed to deep localized quantum dot states.