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HL: Halbleiterphysik

HL 10: Baulemente

HL 10.1: Vortrag

Montag, 8. März 2004, 15:15–15:30, H13

Efficiency of High-Brightness AlGaInP LEDs: Model and Experiment — •P. Altieri, A. Jaeger, R. Windisch, N. Linder, P. Stauss, R. Oberschmid, and K. Streubel — OSRAM Opto Semiconductors GmbH, Wernerwerkstr. 2, 93049 Regensburg

We present a quantitative analysis of the internal quantum efficiency of high-brightness AlGaInP light-emitting devices (LEDs) with an emission wavelength ranging from 650 nm to 560 nm. The wavelength is adjusted by varying the Aluminum content in the active region. The evaluation is based on measurements of the external quantum efficiency of the LEDs as a function of the operating current (0.1-20 mA) and temperature (298-360 K). The determination of the internal quantum efficiency is performed by means of a model that takes into account the radiative and nonradiative recombination in the active layer, the diffusive leakage of charge carriers into the confining InAlP layers and the influence of photon recycling on the light extraction efficiency. In the current range here analyzed red emitting LEDs show maximum internal quantum efficiencies close to 100 %. The maximum efficiency decreases with decreasing wavelength down to about 7 % for green LEDs. This reduction is mainly due to leakage which accounts for the loss of about 75 % of the injected carriers. In addition, the nonradiative recombination increases by approximately one order of magnitude from red to green LEDs.