Effect of high-temperature/current stress on the forward tunneling current of InGaN/GaN high-power blue-light-emitting diodes

Abstract

Through the analysis of the temperature-dependent current–voltage (I–V) characteristics of the fabricated InGaN/GaN high-power blue-light-emitting diodes (LEDs), the low-bias region was confirmed to be dominated by tunneling current, while the medium-bias region was dominated by diffusion-recombination current. Electrons and heavy holes appeared to play similar roles in the tunneling current of the fabricated LEDs, with no apparent dominant tunneling entity determined by characteristic energy as previous works suggested. After 1000 h of high-temperature/current stress, the medium-bias regions of the I–V curves of LEDs remained almost unchanged, while the current in the low-bias region was greatly enhanced by the stress, which confirmed the different carrier transport mechanism behaviors in the low- and medium-bias regions. Further comparison between the I–V characteristics of the unstressed and stressed LEDs suggested that the change in I–V curve was associated with the increase in defect density and the apparent doping concentration in the InGaN/GaN multiple-quantum-well (MQW) active region.

Significant improvement of reverse leakage current characteristics of Si-based homoepitaxial InGaN/GaN blue light emitting diodes

“…As a result, LED II possesses more than 3 orders higher reverse leakage current magnitude, compared to that of LED I over wide range of temperature. This is in good agreement with the recent literature 32 . Additionally, a reduced density of deep trap levels in the homoepitaxial InGaN/GaN LEDs assist a decrease in a tunneling probability of carriers into the conduction band edge of the p-GaN layers.…”

Reverse leakage current characteristics of InGaN/GaN multiple quantum well ultraviolet/blue/green light-emitting diodes

“…[7][8][9] Temperature-dependent current-voltage (I-V ) measurement was used to elucidate the mechanisms of leakage current. [10][11][12][13] Several physical models such as variable-range hopping (VRH) conduction, 14,15) nearest-neighbor hopping (NNH) conduction, 16,17) space-charge-limited conduction, 9) field-emission tunneling, 18) interband tunneling, 19) and Poole-Frenkel emission 10) have been suggested as the mechanisms of the reverse leakage current in GaN-based LEDs. Researchers believed that the reverse leakage current is closely related to the defect density, but unanimously acknowledged that the carrier transport mechanism behind the reverse leakage current is yet to be elucidated.…”

Comparative study of GaN-based ultraviolet LEDs grown on different-sized patterned sapphire substrates with sputtered AlN nucleation layer

“…The efficiency of GaNbased UV LEDs with lower In content in InGaN=AlInGaN multiple quantum wells (MQWs) is more sensitive to dislocation-related nonradiative recombination centers than that of GaN-based blue LEDs. [16][17][18][19][20][21][22] Therefore, the performance of UV LEDs is limited by the high density of TDs in GaN epitaxial layers, resulting in a low internal quantum efficiency (IQE). Improving the crystalline quality of GaN epitaxial layers is effective in enhancing the efficiency of UV LEDs.…”