High hole concentration in Mg-doped AlN/AlGaN superlattices with high Al content

Ebata, K.; Nishinaka, Junichi; Taniyasu, Yoshitaka; Kumakura, Kazuhide

doi:10.7567/jjap.57.04fh09

Cited by 48 publications

(27 citation statements)

References 35 publications

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“…Afterward, the internal quantum efficiency can be strongly increased and the efficiency droop eliminated using such a graded AlGaN layer instead of a traditional AlGaN electron-blocking layer (EBL) [62]. Numerous designs, including AlGaN superlattices and graded layers [53,[63][64][65], have been demonstrated to allow the polarization fields to assist the ionization of Mg acceptors. To overcome the problem of solubility [66] and tendency of self-compensation, delta-doping, or modulation-doping techniques have been investigated for p-AlGaN.…”

Section: Carrier Transport and Internal Quantum Efficiencymentioning

confidence: 99%

Perspectives on UVC LED: Its Progress and Application

et al. 2021

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High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields.

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Section: Carrier Transport and Internal Quantum Efficiencymentioning

confidence: 99%

Perspectives on UVC LED: Its Progress and Application

et al. 2021

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“…A high amount of Al affects the solubility of the Mg in p‐type AlGaN. [ 25 ] Moreover, due to valence band offset at the AlGaN electron blocking layer (EBL) and active region interface, the injection of holes into the active region is badly affected and fewer holes reach the AlGaN‐based active region. [ 19 ]…”

Section: P‐type Doping Problems In Algan‐based Light‐emitting Diodesmentioning

confidence: 99%

AlGaN‐based ultraviolet light‐emitting diodes: challenges and opportunities

2020

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Due to low power consumption, tunable wavelength and long lifetime ultraviolet light‐emitting diodes (UV LEDs) have found many applications in different fields such as health care, water disinfection, agriculture. In this review, we report different problems that lead to low external quantum efficiency of UV LEDs. We also report various challenges in the growth process of the UV LEDs such as increase in the dislocation density, which affects the optoelectronic performance of the devices. We also report the analysis of the two modes of light polarization, i.e. transverse electric and transverse magnetic in UV LEDs. Moreover, we also summarize various state‐of‐the‐art reported external quantum efficiencies, light output power and peak emission wavelengths in the three UV wavelength regimes, i.e. UV‐A, UV‐B and UV‐C LEDs.

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“…to AlGaN. The generation of a 2D hole gas has been confirmed in the AlGaN/AlN superlattice structure with the general þc-plane, and this technique led to the demonstration of a deep ultraviolet laser diode; [26][27][28][29] the generation of a 2DEG using the N-polar (Al)GaN/AlN structure was caused by the inverted structure toward the þc-plane.…”

Section: Introductionmentioning

confidence: 99%

Growth and Characterization of Nitrogen‐Polar AlGaN/AlN Heterostructure for High‐Electron‐Mobility Transistor

Ito

Sakamoto

Isono

et al. 2020

Physica Status Solidi (b)

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A nitrogen‐polar (N‐polar) AlGaN/AlN high‐electron‐mobility transistor (HEMT) is proposed, and the generation of a 2D electron gas (2DEG) is simulated. The band diagram of N‐polar (Al)GaN/AlN shows the generation of the 2DEG, whereas that of the conventional metal‐polar (Al)GaN/AlN structure shows the generation of a 2D hole gas. Furthermore, the concentration of the 2DEG is considerably high even when the (Al)GaN layer is as thin as a few nanometers. N‐polar AlGaN/AlN is grown on sapphire substrates with a misorientation angle of 2°; furthermore, atomic force microscope measurements in a range of 5 × 5 μm2 demonstrate that the root‐mean‐square value obtained from atomic force microscopy of N‐polar AlGaN is approximately 0.7 nm. N‐polar AlGaN layers with a thickness of approximately 40–60 nm with more than 50% Al content are almost coherently grown on the N‐polar AlN layer with a thickness of approximately 400 nm.

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High hole concentration in Mg-doped AlN/AlGaN superlattices with high Al content

Cited by 48 publications

References 35 publications

Perspectives on UVC LED: Its Progress and Application

Perspectives on UVC LED: Its Progress and Application

AlGaN‐based ultraviolet light‐emitting diodes: challenges and opportunities

Growth and Characterization of Nitrogen‐Polar AlGaN/AlN Heterostructure for High‐Electron‐Mobility Transistor

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