Efficiency improvement of AlGaN-based deep ultraviolet LEDs with gradual Al-composition AlGaN conduction layer

Huang, Ping-yang; Xiao, Longfei; Chen, Xiufang; Wang, Qing-pu; Xu, M.; Xu, Xiangang; Huang, Jing

doi:10.1007/s11801-020-0072-4

Cited by 6 publications

(3 citation statements)

References 29 publications

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“…Countless efforts have been conducted to specify the desired wavelength and the PL intensity of DUV-LED [14,15]. Most works focus on the types of material used to generate the UV spectrum, such as the near UVLED, Indium Gallium Nitride (InGaN) [16][17][18], and the DUV-LED Aluminium Gallium Nitride (AlGaN) [11,[19][20][21][22][23][24]. The width of the quantum well also plays a role in deciding the emitted UV-spectrum [25].…”

Section: Introductionmentioning

confidence: 99%

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Aman¹,

Fajri²,

Noorden³

et al. 2022

Phys. Scr.

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We report a numerical analysis of the variation of Aluminium (Al) composition in Al Gallium Nitride (AlGaN)-based Deep-Ultraviolet Light-Emitting Diode (DUV-LED) and its effects on the carrier concentration, radiative recombination, and photoluminescence (PL). Three different structures with different Al compositions are compared and analyzed. The radiative recombination of the DUV-LED is less efficient due to the imbalance of carrier distribution. The findings show that the uniform electrons and holes distribution significantly improve the radiative recombination for structure with a thin step-shaped quantum well (QW). The simulated structure emits a wavelength of 302.874 nm, categorized in the ultraviolet-B (UV-B) spectrum. Our results imply that carrier uniformity in QW is required to enhance the light intensity of DUV-LED. Remarkably, the uniformity enhances the PL intensity drastically, at least six times higher than the first structure and twice higher than the second structure.

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Section: Introductionmentioning

confidence: 99%

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Aman¹,

Fajri²,

Noorden³

et al. 2022

Phys. Scr.

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“…To further explore the underlying mechanism influencing the variation of EQE with chip size, simulations on IQE were performed through Crosslight software [29], by setting the A, B and C coefficients of the UV-C micro-LEDs to be the same, i.e. A = 5 × 10 6 s −1 , B = 2 × 10 −11 cm 3 s −1 and C = 10 −30 cm 6 s −1 , and the LEE was simulated through Tra-cePro software.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the efficiency improvement of 273 nm AlGaN UV-C micro-LEDs

Qian¹,

Zhu²,

Shan³

et al. 2022

J. Phys. D: Appl. Phys.

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UV-C LEDs have great application prospects in the fields of sterilization, disinfection, and non-line-of-sight solar-blind communication. However, the efficiency is not high enough to satisfy the applications and needs to be improved. In this work, AlGaN based UV-C LEDs (273 nm) with size from 8 to 200 μm were fabricated to evaluate the size effect of external quantum efficiency (EQE). Higher EQE was detected in smaller-size UV-C micro-LEDs. Simulations on EQE were performed. The analysis on experimental data and the simulation results reveals that higher EQE originates from both higher internal quantum efficiency (IQE) at high current densities due to better current spreading and higher light extraction efficiency (LEE) due to larger proportion of the sidewall. From the efficiency improvement mechanism, it is concluded that the severer current density non-uniformity and LEE loss of UV-C devices compared with visible or near ultraviolet LEDs can be effectively restrained by preparing micro-LEDs. Our work helps to optimize the efficiency characteristics for UV-C applications.

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“…Moreover, the LEE of NUV LEDs is lower than that of blue LEDs owing to self-absorption in the top p-GaN contact layer [9]. Several research groups have attempted to increase the IQE of NUV LEDs by employing AlGaN quantum barriers (QBs) that replace the conventional GaN QBs and AlGaN electron blocking layer (EBL) [13,14]. Even though the efficiency of NUV LEDs has been improved via AlGaN QBs and EBL, the benefit is less than expected.…”

Section: Introductionmentioning

confidence: 99%

Improved performance of InGaN/GaN Near-UV light-emitting diodes with staircase hole injector

Kim

et al. 2021

Eng. Res. Express

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We report the enhanced performance of near-ultraviolet (NUV) InGaN/GaN multiple quantum-well (MQW) light-emitting diodes (LEDs) with a staircase hole injector (SHI). Simulation results indicate that the internal electrostatic field in the QW of the LED-SHI is decreased owing to the reduced sheet charge density at the interface between QW and quantum barrier (QB) caused by the smaller In content difference. Additionally, the SHI structure in the QBs suppresses the ballistic or quasi-ballistic hole transport, thus enhancing efficient hole injection into the QWs. The radiative output power of an LED-SHI is increased by 25.3% at 300 mA over that of conventional LEDs with GaN QBs. The droop of internal quantum efficiency (IQE) an LED-SHI at 300 A·cm−1 is 6.1%, while the LED with GaN QBs has an IQE droop of 17.7%. The reduced IQE droop and increased radiative output power in the LED-SHI is attributed to the reduced hole overflow, increased hole injection into the MQW and the decreased electrostatic field in the MQWs. The results show that the SHI structure in the LED is promising for improved performance in high-power GaN-based NUV LEDs.

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Efficiency improvement of AlGaN-based deep ultraviolet LEDs with gradual Al-composition AlGaN conduction layer

Cited by 6 publications

References 29 publications

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

High photoluminescence intensity of heterostructure AlGaN-based DUV-LED through uniform carrier distribution

Analysis of the efficiency improvement of 273 nm AlGaN UV-C micro-LEDs

Improved performance of InGaN/GaN Near-UV light-emitting diodes with staircase hole injector

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