Hopping transport in the space-charge region of p-n structures with InGaN/GaN QWs as a source of excess 1/f noise and efficiency droop in LEDs

Abstract

It is shown that the emission efficiency and the 1/f noise level in light emitting diodes with InGaN/GaN quantum wells correlate with how the differential resistance of a diode varies with increasing current. Analysis of the results shows that hopping transport via defect states across the n type part of the space charge region results in limitation of the current by the tunneling resistance at intermediate currents and shunting of the n type barrier at high currents. The increase in the average number of tunneling electrons suppresses the 1/f current noise at intermediate currents. The strong growth in the density of current noise at high currents, S J ∝ J 3 , is attributed to a decrease in the average number of tunneling electrons as the n type barrier decreases in height and width with increasing forward bias. The tunneling recombination leakage cur rent along extended defects grows faster than the tunneling injection current, which leads to emission effi ciency droop.

Research on Degradation of GaN-Based Blue LED Caused by γ Radiation under Low Bias

“…It has been pointed out in many literatures [11,[15][16][17][18][19][20][21][22] that the trap-assisted tunneling current is the main component of the GaN-based LED current when it is biased forward at low voltage (generally less than its turn-on voltage). Recently, it was shown that Hurkx's trap-assisted tunneling model [24] might have been applied to GaN PN junctions [25][26][27].…”

“…In this paper, the degradation mechanism of 1/f noise in GaN multiquantum-well blue LEDs caused by c radiation is studied. Often, a typical I-V curve of GaN-based LEDs can be divided into three regions when they operate at the forward bias [11,[15][16][17][18][19][20][21][22],that is, the tunneling current region, the diffusion-recombination current region, and the series resistance region. e mechanism of current and 1/f noise in these three parts is different, so the degradation mechanism after c radiation may be different.…”

Research on 1/f noise degradation of GaN LED caused by γ radiation under high bias

“…In particular, the 1/f noise has been found suitable for the study of the physical mechanisms of degradation caused by radiation. There are many studies on low-frequency noise characterization of GaN-based LEDs [12][13][14][15][16]. Nevertheless, there are very few papers in which the degradations of 1/f noise caused by γ radiation in LEDs are investigated.…”