Performance improvement of AlGaN-based deep-ultraviolet light-emitting diodes via asymmetric step-like AlGaN quantum wells

Lü, Lin; Wan, Zhi; Xu, Fujun; Wang, Xinqiang; Lv, Chen; Shen, Bo; Jiang, Ming; Chen, Qigong

doi:10.1016/j.spmi.2017.02.035

Cited by 19 publications

(6 citation statements)

References 19 publications

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“…It is important that these staggered structures are not only profitable for radiative recombination, but also effective for short-wavelength UV emission. [51,52] It is worth noting that, with increasing Al composition to 100%, the wavefunction overlap in the QW region monotonically reduces due to the weakened carrier confinement. However, the applicability of the simulations based on the k•p method tends to decrease as the QW thickness is reduced to 1 ML.…”

Section: Resultsmentioning

confidence: 99%

High‐Efficiency E‐Beam Pumped Deep‐Ultraviolet Surface Emitter Based on AlGaN Ultra‐Thin Staggered Quantum Wells

Wang

Yuan

Tao

et al. 2022

Advanced Optical Materials

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lifetime, [1][2][3] high stability, [4] and application flexibility. [5] The ones with an emission wavelength of ≈250 nm exhibit the predominant advantage of sterilization, especially for inactivating Bacillus subtilis spores. [6][7][8] Unfortunately, the LEDs with shorter emission wavelength (≤250 nm) present terrible wall-plug-efficiency (WPE), which is less than 1%, [1][2][3] due to poor hole injection efficiency, [9] strong quantum-confined Stark effect (QCSE), [10][11][12][13][14][15][16] and p-GaN electrode induced UV-absorption. [17][18][19][20][21] Moreover, such low WPE results in a huge amount of heat at a large injection current and hinders the device's reliability, thus obstructing the fabrication of a highpower-density integrated UV light source.In order to disregard the above-mentioned issues, the electron beam-pumped deep-ultraviolet surface emitter (DUVSE) is proposed to increase the output power and avoid the conventional carrier injection layers. [22][23][24][25][26][27][28] The device merely consists of a carbon nanotube (CNT) field emitter and AlGaN multiple quantum wells (MQWs). This DUVSE announces plenty of advantages such as low emitted light re-absorption, [24] simple epitaxial structure, [23] and solo-device fabrication at wafer-scale. [22] In A 2-inch wafer-scale electron-beam (e-beam) pumped deep-ultraviolet surface emitter (DUVSE) with high efficiency and high output power at an emission wavelength of 248 nm is reported. This DUVSE benefits from ultra-thin staggered AlN/AlGaN/GaN multiple quantum wells (MQWs), which compromise the electron-hole overlap and carrier confinement and thus significantly improve the emission efficiency. The wall-plug-efficiency (WPE) is increased by six times to 5.25% in comparison to that of conventional DUV lightemitting devices (LEDs) based on AlGaN MQWs. This WPE is achieved under an anode voltage and current of 8 kV and 1 mA, where the output power is 420 mW. This output power can be further enhanced to 702 mW by increasing the anode current to 3 mA. The enhanced WPE and uniform electron beam distribution lighten the avenue to achieve a wafer-scale high power dense DUV light source, which is a challenge for conventional DUV-LEDs, in particular with an emission wavelength of less than 250 nm.

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Section: Resultsmentioning

confidence: 99%

High‐Efficiency E‐Beam Pumped Deep‐Ultraviolet Surface Emitter Based on AlGaN Ultra‐Thin Staggered Quantum Wells

Wang

Yuan

Tao

et al. 2022

Advanced Optical Materials

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“…Aside from the EBL structure adjustments, re-designing the QWs-QB also appears to be a viable strategy to improving optical properties. Compositionally scaled QBs [11], delta-accelerating QBs [12], graduated w-shaped quantum wells (QWs) [13], stride QWs [14], [15], and AlN-Δ-GaN QWs [16], [17], chirping in QBs [18] are among the active region designs being investigated. Aside from the preceding example, Zhang et al proposed other speci c structure concepts that enhanced hole conveyance.…”

Section: Introductionmentioning

confidence: 99%

Efficiency droop free UV-C LED by introducing p-doped LQB and p-n-p-n-p doped AlGaN hole injection layer

Mazumder,

Sapra,

Chahun

et al. 2023

Opt Quant Electron

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The photosensitive and electrical characteristics of almost e ciency-droop-free UV-C LEDs with a Mgdoped LQB and Si-doped shallow periodic electron injection layer in between Mg-doped EBL and Hole injection layer are studied numerically in order to enhance the optical and electrical performance.SiLENSe software is used to look into the QB-QWs region's IQE, energy band pro les, electron and hole concentration, and radiative recombination rates. The ndings show that the proposed UV-C LED has peak IQE 140% higher than the reference one, which is generally related to the improvement of electron and hole function overlapping in QB-QWs region. The proposed modi cation would decrease hole barrier depth by 64% in LQB-EBL, which is what causes the 190% better hole injection from Mg-doped layer.

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“…Zhang et al proposed a DUV LED structure with air cavity extractor, which can significantly improve the extraction efficiency of TM/TE polarized light. [8] In addition, in order to improve the luminous efficiency of LED, other structure designs have also been reported in the literature, such as the multi-quantum barrier electron blocking layer structure, [9] the type-II QW structure, [5,10] AlN-delta-GaN QW structure, [11] step-like QW structure, [12,13] and Al composition-graded p-AlGaN cladding layer structure. [14] In our previous work, we reported the effects of Alcontent in the barrier layer on the optical properties of Al 0.35 Ga 0.65 N/Al x Ga 1−x N QW structure.…”

Section: Introductionmentioning

confidence: 99%

Optical polarization characteristics for AlGaN-based light-emitting diodes with AlGaN multilayer structure as well layer*

Xue¹,

Li²,

Ge³

et al. 2021

Chinese Phys. B

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The optical properties of AlGaN-based quantum well (QW) structure with two coupled thin well layers are investigated by the six-by-six K – P method. Compared with the conventional structure, the new structure, especially the one with lower Al-content in the barrier layer, can enhance the TE-/TM-polarized total spontaneous emission rate due to the strong quantum confinement and wide recombination region. For the conventional QW structure, the reduction of well thickness can lead the degree of polarization (DOP) to decrease and the internal quantum efficiency (IQE) to increase. By using the coupled thin well layers, the DOP for the structure with high Al-content in the barrier layer can be improved, while the DOP will further decrease with low Al-content in the barrier layer. It can be attributed to the band adjustment induced by the combination of barrier height and well layer coupling. The IQE can also be further enhanced to 14.8%–20.5% for various Al-content of barrier layer at J = 100 A/cm2. In addition, the efficiency droop effect can be expected to be suppressed compared with the conventional structure.

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Performance improvement of AlGaN-based deep-ultraviolet light-emitting diodes via asymmetric step-like AlGaN quantum wells

Cited by 19 publications

References 19 publications

High‐Efficiency E‐Beam Pumped Deep‐Ultraviolet Surface Emitter Based on AlGaN Ultra‐Thin Staggered Quantum Wells

High‐Efficiency E‐Beam Pumped Deep‐Ultraviolet Surface Emitter Based on AlGaN Ultra‐Thin Staggered Quantum Wells

Efficiency droop free UV-C LED by introducing p-doped LQB and p-n-p-n-p doped AlGaN hole injection layer

Optical polarization characteristics for AlGaN-based light-emitting diodes with AlGaN multilayer structure as well layer*

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