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

The effect of hot electrons on electroluminescence of in-plane double heterostructure light emitting diode's (with a single 6 nm active layer of In0.20Ga0.80N) is investigated. Diodes with an electron blocking layer (Al0.15Ga0.85N) 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 explained 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 In0.20Ga0.80N diodes with the Al0.15Ga0.85N blocking layer.