Enhanced Emission Efficiency of Deep Ultraviolet Light-Emitting AlGaN Multiple Quantum Wells Grown on an N-AlGaN Underlying Layer

Li, Lei; Miyachi, Yuta; Miyoshi, Makoto; Egawa, Takashi

doi:10.1109/jphot.2016.2601439

Cited by 7 publications

(6 citation statements)

References 50 publications

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“…There could be two reasons to explain it. The first reason is the formation of quantum-confined Stark effect (QCSE) in the structure without the AlN SLs, which causes the band tilt 23 , 24 . Second, due to the higher defect density of AlN epilayer without the insertion of AlN SLs, the quality of the AlGaN MQWs was lower.…”

Section: Resultsmentioning

confidence: 99%

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering

Wang

Tasi

Lin

et al. 2017

Sci Rep

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In this study, high internal-quantum-efficiency (IQE) AlGaN multiple quantum wells (MQWs) were successfully demonstrated on low-defect-density AlN templates with nano-patterned sapphire substrates. These templates consisted of AlN structures with 0∼30 periods superlattices (SLs) by alternating high (100) and low (25) V/III ratios under a low growth temperature (1130 °C). Compared to conventional high crystal-quality AlN epilayers achieved at temperatures ≥1300 °C, lower thermal budget can reduce the production cost and wafer warpage. Via optimization of the SL period, the AlN crystallinity was systematically improved. Strong dependence of SL period number on the X-ray full-width-at-half-maximum (FWHM) of the AlN epilayer was observed. The AlN template with 20-period SLs exhibited the lowest FWHM values for (0002) and (10ī2), namely 331 and 652 arcsec, respectively, as well as an ultra-low etching pit density of 1 × 105 cm−2. The relative IQE of 280 nm AlGaN MQWs exhibited a dramatically increase from 22.8% to 85% when the inserted SL increased from 0 to 20 periods. It has hardly ever been reported for the AlGaN MQW sample. The results indicate that the engineered AlN templates have high potential applications in deep ultraviolet light emitters.

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Section: Resultsmentioning

confidence: 99%

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering

Wang

Tasi

Lin

et al. 2017

Sci Rep

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“…A most convenient method to suppress the polarization induced electric field is doping the quantum barriers by Si dopants, such that free electrons released by the Si dopants can compensate the polarization induced charges at the interface for the quantum barrier/quantum well pairs. Li et al demonstrate that the polarization induced electric field in the quantum well becomes weak when n‐AlGaN underlying layer is grown before the MQWs stack . They also suggest that the AlN composition for the n‐AlGaN underlying layer is lower than that for the n‐AlGaN template.…”

Section: Screen the Polarization Induced Electric Field Within The Mqmentioning

confidence: 99%

Progress in External Quantum Efficiency for III‐Nitride Based Deep Ultraviolet Light‐Emitting Diodes

Chu

Tian

Zhang

et al. 2019

Physica Status Solidi (a)

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AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) are featured with small size, DC driving, no environmental contamination etc., and they are now emerging as the excellent solid-state light source to replace the conventional mercury based light tubes. Nevertheless, the DUV LEDs are currently affected by the poor external quantum efficiency (EQE), which is caused by the low internal quantum efficiency (IQE) and the very unsatisfying light extraction efficiency (LEE). In this work, the authors disclose the underlying mechanism for the low EQE and summarize the technologies that have been adopted so far for enhancing the EQE.

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“…The generated photon number is decided by the radiative recombination rate, which is formulated by B × N 2 (B denotes the radiative recombination coefficient and N represents the carrier concentration). The radiative recombination coefficient is remarkably influenced by the polarization induced electric field in the [0001] oriented AlGaN-based MQWs by means of spatially separating electron and hole wave functions [ 18 , 19 , 20 ]. The other concern comes from the injection efficiency for electrons and holes [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

On the Hole Injection for III-Nitride Based Deep Ultraviolet Light-Emitting Diodes

Zhang

et al. 2017

Materials

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The hole injection is one of the bottlenecks that strongly hinder the quantum efficiency and the optical power for deep ultraviolet light-emitting diodes (DUV LEDs) with the emission wavelength smaller than 360 nm. The hole injection efficiency for DUV LEDs is co-affected by the p-type ohmic contact, the p-type hole injection layer, the p-type electron blocking layer and the multiple quantum wells. In this report, we review a large diversity of advances that are currently adopted to increase the hole injection efficiency for DUV LEDs. Moreover, by disclosing the underlying device physics, the design strategies that we can follow have also been suggested to improve the hole injection for DUV LEDs.

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Enhanced Emission Efficiency of Deep Ultraviolet Light-Emitting AlGaN Multiple Quantum Wells Grown on an N-AlGaN Underlying Layer

Cited by 7 publications

References 50 publications

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering

Progress in External Quantum Efficiency for III‐Nitride Based Deep Ultraviolet Light‐Emitting Diodes

On the Hole Injection for III-Nitride Based Deep Ultraviolet Light-Emitting Diodes

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