Increasing the Carrier Injection Efficiency of GaN-Based Ultraviolet Light-Emitting Diodes by Double Al Composition Gradient Last Quantum Barrier and p-Type Hole Supply Layer

Wu, Jinxing; Li, Peixian; Zhou, Xiaowei

doi:10.1109/jphot.2021.3058651

Cited by 6 publications

(5 citation statements)

References 29 publications

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“…Consequently, it may significantly compromise both the electron blocking and hole injection processes, ultimately resulting in a diminished optical power and efficiency [22]. As a result, many strategies aimed at improving the amount of droop utilize either an Al composition gradient [23][24][25] or a final barrier with a different thickness [23,26,27] as a workaround for this issue. In a previous study we reported high−performance green LEDs employing heterojunction−type last quantum barrier layers [28].…”

Section: Device Structure and Parametersmentioning

confidence: 99%

Enhancing the Performance of GaN-Based Light-Emitting Diodes by Incorporating a Junction-Type Last Quantum Barrier

Wang,

Xu,

Wang

et al. 2024

Electronics

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In this paper, an n-i-p-type GaN barrier for the final quantum well, which is closest to the p-type GaN cap layer, is proposed for nitride light-emitting diodes (LEDs) to enhance the confinement of electrons and to improve the efficiency of hole injection. The performances of GaN-based LEDs with a traditional GaN barrier and with our proposed n-i-p GaN barrier were simulated and analyzed in detail. It was observed that, with our newly designed n-i-p GaN barrier, the performances of the LEDs were improved, including a higher light output power, a lower threshold voltage, and a stronger electroluminescence emission intensity. The light output power can be remarkably boosted by 105% at an injection current density of 100 A/cm2 in comparison with a traditional LED. These improvements originated from the proposed n-i-p GaN barrier, which induces a strong reverse electrostatic field in the n-i-p GaN barrier. This field not only enhances the confinement of electrons but also improves the efficiency of hole injection.

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Section: Device Structure and Parametersmentioning

confidence: 99%

Enhancing the Performance of GaN-Based Light-Emitting Diodes by Incorporating a Junction-Type Last Quantum Barrier

Wang,

Xu,

Wang

et al. 2024

Electronics

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“…16 Hao et al employed double-stepped AlN composition last quantum barrier and stepped AlN composition HSL in AlGaN UV LED to increase carrier injection efficiency. 17 Akasaki et al adopted the stepped AlN composition HSL idea for AlGaN UV laser diode (LD), and they believed that the stepped AlN composition HSL and its thickness significantly affect the gain and carrier injection of AlGaN UV LD. 18 The above research show that researchers have enhanced the hole injection efficiency by improving p-EBL or p-HSL, but for LEDs with shorter wavelengths, it is not sufficient to optimize a single p-EBL or p-HSL.…”

Section: Introductionmentioning

confidence: 99%

“…Hao et al. employed double-stepped AlN composition last quantum barrier and stepped AlN composition HSL in AlGaN UV LED to increase carrier injection efficiency 17 . Akasaki et al.…”

Section: Introductionmentioning

confidence: 99%

Increasing the hole energy by the p-type dual polarization for high internal quantum efficiency of 237 nm-band deep ultraviolet light-emitting diodes

Xing,

Zhang,

et al. 2024

Opt. Eng.

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Aluminum-rich p-AlGaN electron-blocking layers (p-EBL) usually block the hole injection in the AlGaN-based deep ultraviolet (DUV) light-emitting diode (LED). Meanwhile, the ionization energy of the magnesium receptors in the aluminum-rich p-AlGaN layer is considerably high, and the conductivity is low, leading to a reduction in the hole injection capability. Consequently, AlGaN-based DUV LEDs suffer from a low internal quantum efficiency (IQE). A structure of p-EBL and hole source layer (p-HSL) using AlN composition gradient AlGaN is proposed. The polarization bulk charges are introduced in both p-EBL and p-HSL (the p-type dual polarization) to shield the polarization-induced electric field and increase the hole energy. Although the single-polarized structure of p-EBL or p-HSL can also effectively enhance the performance of the device, calculation results indicate that the performance of the p-type dual-polarized structure can be doubled. This is because optimizing a single p-EBL or p-HSL can only introduce polarization bulk charge in the monolayer but not in all p-type regions. Therefore, in LEDs with shorter wavelengths, to maximize the hole energy, a dual-polarization structure should be adopted for the p-type region. Based on this, a maximum IQE of 55.65% and an efficiency droop of 4.84% are obtained at a wavelength of 237 nm. Findings of this study provide insights to solve the problem of low IQE in high-performance DUV LEDs.

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“…In recent study, Khan et al studied the influence of graded AlGaN HSL on turn-on voltage and carrier injection of UV LED [29]. This idea was extended by Hao et al to maximize the carrier injection efficiency by using double graded last quantum barrier (LQB) with graded HSL for AlGaN UV LED [30]. Similarly, Akasaki et al uses the HSL grading idea for AlGaN UV LDs and urges that AlGaN HSL grading and thickness have high impact on AlGaN UV LD gain ad confinement [31].…”

Section: Introductionmentioning

confidence: 99%

Compositionally graded AlGaN hole source layer for deep-ultraviolet nanowire light-emitting diode without electron blocking layer

Sharif¹,

Usman²,

Niass³

et al. 2021

Nanotechnology

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The electron blocking layer (EBL) plays a vital role in blocking the electron overflow from an active region in the AlGaN-based deep-ultraviolet light-emitting diode (DUV-LED). Besides the blocking of electron overflow, EBL reduces hole injection toward the active region. In this work, we proposed a DUV nanowire (NW) LED structure without EBL by replacing it with a compositionally continuous graded hole source layer (HSL). Our proposed graded HSL without EBL provides a better electron blocking effect and enhanced hole injection efficiency. As a result, optical power is improved by 48% and series resistance is reduced by 50% with 4.8 V threshold voltage. Moreover, graded HSL without EBL offer reduced electric field within the active region, which leads to a significant increment in radiative recombination rate and enhancement of spontaneous emission by 34% at 254 nm wavelength, as a result, 52% maximum internal quantum efficiency with 24% efficiency drop is reported.

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Increasing the Carrier Injection Efficiency of GaN-Based Ultraviolet Light-Emitting Diodes by Double Al Composition Gradient Last Quantum Barrier and p-Type Hole Supply Layer

Cited by 6 publications

References 29 publications

Enhancing the Performance of GaN-Based Light-Emitting Diodes by Incorporating a Junction-Type Last Quantum Barrier

Enhancing the Performance of GaN-Based Light-Emitting Diodes by Incorporating a Junction-Type Last Quantum Barrier

Increasing the hole energy by the p-type dual polarization for high internal quantum efficiency of 237 nm-band deep ultraviolet light-emitting diodes

Compositionally graded AlGaN hole source layer for deep-ultraviolet nanowire light-emitting diode without electron blocking layer

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