Auger-generated hot carrier current in photo-excited forward biased single quantum well blue light emitting diodes

Abstract

We report on measurements of the photo-modulated current-voltage and electroluminescence characteristics of forward biased single quantum well, blue InGaN/GaN light emitting diodes with and without electron blocking layers. Low intensity resonant optical excitation of the quantum well was observed to induce an additional forward current at constant forward diode bias, in contrast to the usual sense of the photocurrent in photodiodes and solar cells, as well as an increased electroluminescence intensity. The presence of an electron blocking layer only slightly decreased the magnitude of the photo-induced current at constant forward bias. Photo-modulation at constant forward diode current resulted in a reduced diode bias under optical excitation. We argue that this decrease in diode bias at constant current and the increase in forward diode current at constant applied bias can only be due to additional hot carriers being ejected from the quantum well as a result of an increased Auger recombination rate within the quantum well.

Evidence for trap-assisted Auger recombination in MBE grown InGaN quantum wells by electron emission spectroscopy

“…Both the geometry of the on-wafer LEDs and the measurement setup are described elsewhere. 29 The EQE measurements are described in the study by Espenlaub et al 30 and are reproduced here (Fig. 2) to show the lack of efficiency droop in these MBE grown LEDs.…”

Disorder effects in nitride semiconductors: impact on fundamental and device properties

“…The main mechanism invoked besides Auger NR recombination is carrier escape from the active region. Experimental evidence was shown to be disputable [61,63] and theoretical support further discussed in the LED simulation section shows it to be negligible.…”

“…Then, theorists calculated the effects of indirect phonon-assisted mechanisms or of QW finite thickness [56][57][58][59], however, still with smaller values than measured ones, which led to continuing disputing the Auger mechanism with others mechanisms such as diminished IE due to carrier escape [53] or overshoot [60] from active regions (see Figure 6). However, the evidence for carriers escaping the active region relied on misleading interpretations of measurements: forward minority electron current in the LED top p-layer can be mistaken for escape current, whereas it is due to Auger electrons bypassing the EBL [61][62][63] (it is remarkable that although Vampola et al [61] concluded that both thermal escape and Auger-assisted electron overflow of electrons could explain his data, most authors citing this article use it as proof of thermal escape of electrons); reverse photocurrent under low bias has been mistaken as an NR recombination channel (for a full discussion of issues in optical measurements, see the study by David et al [49]).…”

Three-Dimensional Numerical Study on the Efficiency Droop in InGaN/GaN Light-Emitting Diodes

“…Theoretical calculations [34] and experimental evidence [8], [9] confirm that the occurrence of Auger recombination will assist electron leakage, also known as direct carrier leakage. Auger recombination generates hot carriers that can be recaptured by the QWs or facilitate electron leakage outside the QWs, as has been found to occur in GaInAsP/InP double-heterostructure LEDs and lasers [35], InGaN/GaN QW(s) blue LEDs [7] and SQW blue LEDs [36].…”