Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 43: GaN: Devices I
HL 43.2: Talk
Thursday, March 30, 2006, 11:15–11:30, BEY 118
Field dependent PL-spectra and emission efficiency of InGaN/GaN-LED-heterostructures — •Harald Braun1, Ulrich T. Schwarz1, Werner Wegscheider1, Elmar Baur2, Uwe Strauß2, and Volker Härle2 — 1Naturwissenschaftliche Fakultät II- Physik, Universität Regensburg Universitätsstr. 31, 93053 Regensburg, Germany — 2OSRAM Opto Semiconductors GmbH, Wernerwerkstr. 2, 93049 Regensburg, Germany
To improve the efficiency of blue and green InGaN/GaN-based LEDs we use field-dependent photoluminescence (PL) experiments to characterize internal electric fields, carrier capture, internal efficiency, and non-radiative recombination. The shape of InGaN/GaN-QWs depends strongly on the external electric field applied to the p-n-junction. We show that applying a forward bias the comparability between PL and EL can be improved, which is important when using PL-data for optimizing EL-efficiency of InGaN/GaN heterostructures. Also, by comparing the field-dependence of the peak-position with simple one-dimensional simulations we determine the size of the piezoelectric fields in InGaN/GaN-quantum wells. From the tunnelling of carriers through the barriers, which causes a strong decrease of the PL-intensity with increasing reverse bias, we estimate the offset-ratio of the InGaN-bandgap.