AlGaN/InGaN/GaN blue light emitting diode degradation under pulsed current stress

Abstract

This study focused on the performance of commercial AlGaN/InGaN/GaN blue light emitting diodes ͑LEDs͒ under high current pulse conditions. The results of deep level transient spectroscopy ͑DLTS͒, thermally stimulated capacitance, and admittance spectroscopy measurements performed on stressed devices, showed no evidence of any deep-level defects that may have developed as a result of high current pulses. Physical analysis of stressed LEDs indicated a strong connection between the high intrinsic defect density in these devices and the resulting mode of degradation.

Effect of long-term aging on series resistance and junction conductivity of high-power InGaN light-emitting diodes

“…Aging is seen to result in a marginal variation of the I-V behaviour at sub-onset currents (δV F ∼ −5 mV at I F = 1 mA), which is probably due to the enhancement of nonradiative recombination and the emergence of ohmic shorts within the chip [6][7][8][9][10][11]. At the nominal current (350 mA), a remarkable drop in forward voltage (δV F = −70 mV) is observed.…”

“…Meanwhile, the effects of aging on electrical characteristics of LEDs are usually categorized as follows [6][7][8][9][10]: (i) an increase of sub-onset forward current due to an occurrence of additional nonradiative recombination routes, (ii) an increase of reverse current, and (iii) a decrease of forward current at nominal voltages mainly due to the deterioration of electrodes and contact layers. An increase of forward current in the entire range of voltages in aged InGaN LEDs was also observed and attributed to an occurrence of dislocation-related ohmic shorts within the chip [11].…”

Electrical Characterization of InGaN/GaN Multiple‐Quantum‐Well Structures by Thermal Admittance Spectroscopy

“…Although one should be careful when using such a method [8], this type of analysis has been applied to QW structures, either to assess the presence of defects [9] or to determine QW parameters [10]. The Arrhenius plot of the cutoff frequencies corresponding to the five RC series circuits, shown in Fig.…”

Luminescence degradation of InGaN/GaN violet LEDs

“…More and more studies have clarified some factors associated with the degradation processes in short-wavelength InGaN/GaN-based LEDs. Dark spot defects [3], contact metal migration [4][5][6], recombination-enhanced defect formation and thermally induced defect formation [7,8] were observed in the processes of luminescence intensity decreases under aging tests of large density current. The indium composition fluctuation is believed to be very important in high-efficiency light-emitting processes of InGaN/GaN MQWs LEDs because localized energy state caused by indium composition fluctuation increases the carrier radiative recombination rate.…”