Bias dependence of internal quantum efficiency and carrier capture in a green (In,Ga)N single‐quantum‐well diode

Abstract

AbstractInternal quantum efficiency (IQE) and vertical capture processes of photogenerated carriers in a c ‐plane green (In,Ga)N single‐quantum‐well light‐emitting‐diode have been investigated by comparing variation in photoluminescence (PL) intensity as a function of applied voltage over a wide temperature range (T = 20‐300 K) under direct (λex =380 nm) and indirect (λex = 325 nm) excitation. Under the direct excitation the PL intensity reflecting IQE shows a maximum value at +2.4 V irrespective of temperatures. However, it decreases to 23% from the maximum as temperature increases to 300 K. The PL intensity reduction observed at the optimized forward bias is much less as temperature increases under the indirect excitation. This difference observed between the two excitation conditions indicates an important role of efficient capture of photogenerated carriers into the active radiative recombination centers from the barriers under the presence of internal polarization fields. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)