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HL: Fachverband Halbleiterphysik
HL 31: Poster I: Devices, Quantum Dots and Quantum Wires
HL 31.12: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D1
Enhanced light emission from nitride based UV light-emitting diodes using multifinger contact geometry — •M. Hoppe1, N. Lobo2, H. Rodriguez1, A. Knauer1, V. Küller1, P. Vogt2, S. Einfeldt1, M. Weyers1, and M. Kneissl1,2 — 1Ferdinand-Braun-Institut für Höchstfrequenztechnik, Berlin, Germany — 2Technische Universität Berlin, Institut für Festkörperphysik, Berlin, Germany
For ultraviolet LEDs, current crowding at the edges of large area contacts is a serious issue due to low mobility and low donor activation in the n-AlGaN current spreading layer resulting in a high resistivity. It is hence necessary to switch from a simple square contact to more sophisticated contact geometries. In this work, the influence of a multifinger contact geometry on the emission characteristics of 320 nm and 380 nm LEDs has been studied. The emission and the heating of LEDs with constant total contact areas but varying finger widths have been investigated. Experimental LI-curves and their thermal roll-over and wavelength shift are compared with simulations of current and heat distribution in the LEDs. Data shows that as the finger width decreases from 150 µm to 10 µm the maximum optical output power, which is limited by the self-heating of the unmounted device, increases by 50% for the 380 nm LED. For the 320 nm LED a rise in power of 44% is found when the finger width decreases from 100 µm to 20 µm. Corresponding simulations reveal that the maximum device temperature decreases with the finger width.