Abstract
The nature of reverse leakage current characteristics in InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN crystals detached from a Si substrate is investigated for the first time, using temperature-dependent current-voltage (T-I-V) measurement. It is found that the Si-based homoepitaxial InGaN/GaN LEDs exhibit a significant suppression of the reverse leakage current without any additional processes. Their conduction mechanism can be divided into variable-range hopping and nearest neighbor hopping (NNH) around 360 K, which is enhanced by Poole-Frenkel emission. The analysis of T-I-V curves of the homoepitaxial LEDs yields an activation energy of carriers of 35 meV at −10 V, about 50% higher than that of the conventional ones (Ea = 21 meV at −10 V). This suggests that our homoepitaxial InGaN/GaN LEDs bears the high activation energy as well as low threading dislocation density (about 1 × 106/cm2), effectively suppressing the reverse leakage current. We expect that this study will shed a light on the high reliability and carrier tunneling characteristics of the homoepitaxial InGaN/GaN blue LEDs produced from a Si substrate and also envision a promising future for their successful adoption by LED community via cost-effective homoepitaxial fabrication of LEDs.
Highlights
Significant development of high luminescence efficiency in InGaN/GaN light emitting diodes (LEDs) has offered new futuristic applications such as automotive headlamps, traffic signals, displays, and general lighting[1,2,3]
Note that the temperature- and field-dependence on the reverse leakage current in LED II appears relatively more severe, compared to that in LED I. We speculate that this is attributed to higher dislocation density in LED II, which can stimulate the field-dependent carrier tunneling at the elevated temperature
We report the reverse leakage characteristics of InGaN/GaN LEDs on FS-GaN peeled off from a Si substrate for the first time, using temperature-dependent current-voltage (T-I-V) measurement
Summary
Received: 5 September 2018 Accepted: 3 January 2019 Published: xx xx xxxx blue light emitting diodes. The nature of reverse leakage current characteristics in InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN crystals detached from a Si substrate is investigated for the first time, using temperature-dependent current-voltage (T-I-V) measurement. The analysis of T-I-V curves of the homoepitaxial LEDs yields an activation energy of carriers of 35 meV at −10 V, about 50% higher than that of the conventional ones (Ea = 21 meV at −10 V) This suggests that our homoepitaxial InGaN/GaN LEDs bears the high activation energy as well as low threading dislocation density (about 1 × 106/cm2), effectively suppressing the reverse leakage current. We expect that this will provide the LED community with the valuable and promising information regarding the device performances of the homoepitaxial InGaN/GaN LEDs. InGaN/GaN multi quantum well (MQW) LEDs with peak emission wavelength of ~440 nm were grown using MOCVD (Aixtron G3 2600) on 2-inch HVPE FS-GaN extracted from a Si substrate (LED I). The defect densities of LED I and LED II were estimated to be 1 × 106 cm−2 and 5 × 108 cm−2, respectively, which was confirmed by micro photoluminescence (PL) mapping. (Not shown in this paper)
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