Trap-assisted tunneling in InGaN/GaN single-quantum-well light-emitting diodes

Abstract

Based on numerical simulation and comparison with measured current characteristics, we show that the current in InGaN/GaN single-quantum-well light-emitting diodes at low forward bias can be accurately described by a standard trap-assisted tunneling model. The qualitative and quantitative differences in the current characteristics of devices with different emission wavelengths are demonstrated to be correlated in a physically consistent way with the tunneling model parameters

Properties of Defective Regions Observed by Photoluminescence Imaging for GaN-Based Light-Emitting Diode Epi-Wafers

“…In the range of the forward bias at which tunneling occurred, SRH nonradiative recombination was the dominant process in the LED operation. The result was consistent with the reports on trap-assisted tunneling, which employed SRH recombination in the models [17][18][19]. As the DSDRs have a high density of nonradiative recombination defects, which affect the chip operation, the adoption of the PL imaging technique to detect DSDRs can provide an effective inspection and a quick evaluation of LED epi-wafers, allowing the estimation of the properties of the LED chips fabricated from the epi-wafers.…”

“…Their result suggested that a high dislocation density could be the reason for the high ideality factors. Recently, forward leakage at low and intermediate bias region has been explained considering trap-assisted tunneling [13,[17][18][19]. The results in this work indicate that the DSDRs in LED-4 are regions of high density of dislocations and deep traps, which cause the forward leakage.…”

“…The n ideal value of the possible parasitic diode was around 18, which was far beyond the n ideal value of LED-1. Auf der Maur et al showed that the n ideal value increased up to 14 for LEDs with QWs having thickness larger than the critical layer thickness [18]. Their result suggested that a high dislocation density could be the reason for the high ideality factors.…”

“…Huge forward leakages up to the intermediate bias region (~1.2-1.9 V) were observed for the chips with DSDRs. Many researches on leakages of nitride based LEDs reported that the leakages resulted from the defects present in the active regions [16][17][18][19][20][21]. Several research groups have studied the abnormality of the I-V curve by employing equivalent-circuit models incorporating a parallel resistance and a parasitic diode [14,[21][22][23].…”

“…Tunneling is another important cause of the forward leakage [17][18][19][20][21]. A parasitic diode-like tunnel current at the low-to-intermediate bias deforms the I-V curves from their typical shapes.…”