The effect of ballistic and quasi‐ballistic electrons on the efficiency droop of InGaN light emitting diodes

Abstract

Abstract The effect of hot electrons on electroluminescence of m ‐plane double heterostructure light emitting diodes (with a single 6 nm active layer of In 0.20 Ga 0.80 N) is investigated. Diodes with an electron blocking layer (Al 0.15 Ga 0.85 N) demonstrate from 3 to 5 times higher electroluminescence efficiency than those without a blocking layer. The lower electroluminescence efficiency in devices without the blocking layer is ex‐ plained in terms of electron overflow caused by ballistic and quasi‐ballistic transport of injected electrons across the InGaN active region. The same mechanism explains the decrease, observed at high current densities, of the electroluminescence efficiency (efficiency droop) in the In 0.20 Ga 0.80 N diodes with the Al 0.15 Ga 0.85 N blocking layer. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)