Origins of Parasitic Emissions from 353 nm AlGaN-based Ultraviolet Light Emitting Diodes over SiC Substrates

Park, Ji‐Soo; Fothergill, D.; Wellenius, Patrick; Bishop, S.M.; Muth, John F.; Davis, R. F.

doi:10.1143/jjap.45.4083

Cited by 20 publications

(12 citation statements)

References 27 publications

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“…The main peak of samples is originated from the active region (MQWs) between 362 and 364 nm. In addition, the EL peak located at around 370 nm for all samples is attributed to the reflection at the GaN underlayer/sapphire interface and the self-absorption in the GaN [13]. The intensity of the main peak increases significantly with the thickness of the undoped Al 0.23 Ga 0.77 N Fig.…”

Section: Resultsmentioning

confidence: 82%

Analysis of the Thickness Effect of Undoped Electron-Blocking Layer in Ultraviolet LEDs

Lin

Wang

Liang

et al. 2014

IEEE Trans. Electron Devices

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In this paper, the thickness effect of an undoped Al 0.23 Ga 0.77 N inserted in the Mg-doped Al 0.23 Ga 0.77 N electronblocking layer (EBL) on the characteristics of the ultraviolet light-emitting diodes (UV-LEDs) was analyzed. The results of secondary-ion-mass spectrometry clearly show that the concentration of Mg back-diffusion from the p-GaN and the Mg-doped EBL decreases with the thickness of an undoped EBL. The radiative recombination rate in the multiple quantum wells (MQWs) can be obviously enhanced after inserting an undoped EBL from the simulated results, and the sample with a 6-nm-thick undoped EBL has the highest radiative recombination rate. It is worth noticing that the hole carrier concentration in the MQWs increases with increasing the thickness of an undoped EBL. The UV-LED possesses 400% enhancement in the output power (at 20 mA) by inserting a 6-nm-thick undoped EBL. The significant enhancement is ascribed to the decrease of nonradiative recombination defects formed by Mg atoms and the increase of hole concentration in the MQWs. Index Terms-Electron-blocking layer (EBL), light-emitting diode (LED), Mg diffusion, simulation, ultraviolet (UV).

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Section: Resultsmentioning

confidence: 82%

Analysis of the Thickness Effect of Undoped Electron-Blocking Layer in Ultraviolet LEDs

Lin

Wang

Liang

et al. 2014

IEEE Trans. Electron Devices

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“…All of these samples correspond to asymmetric EL spectra with shoulder peaks around at 400 nm to 415 nm. These shoulder peaks supposedly originate from the absorption and re-emission of p-GaN layer [11]. The so-called parasitic emissions could cause a little bit broad to EL peaks, which were displaying a FWHM of approximately 13 nm.…”

Section: Resultsmentioning

confidence: 99%

Improved performance of near-ultraviolet InGaN/AlGaN LEDs with various insertion structures

et al. 2010

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In this study, two approaches using various insertion structures are proposed for the near-UV LEDs. One is through a single MOCVD process where a heavily Mg-doped GaN insertion layer (HD-IL) technique is employed to improve crystalline quality of the GaN layer and followed by rest of required GaN-based LED structure. Another approach was demonstrated by the near-UV LEDs with an embedded distributed SiO 2 -disk structure. The periodically spaced hexagonal disk-shaped SiO 2 mask array was deposited on the GaN/sapphire template and followed by the MOCVD regrowth process. These improvements contribute the high-performance 380-nm LEDs with enhanced output powers by 20-40% in magnitude.

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“…A typical example of parasitic emission in the output spectrum of UV-C LED is shown in Figure 6c [23]. Parasitic emission is dominant at a low forward current (<5 mA) [36] and is predominantly caused by the presence of undesirable bands of lower energy bands in the emitting semiconductor [37,38,39] or the presence of fluorescence or phosphorescence contaminant in LED structure [40]. Recently, aluminum nitride-based (AlN) LEDs have been developed, which give high optical power out (1.5 mW, 100 mA) with a low value of parasitic emission in comparison with sapphire-based LEDs (30 mA).…”

Section: Uv Sourcesmentioning

confidence: 99%

Gas Detection Using Portable Deep-UV Absorption Spectrophotometry: A Review

Khan

Newport

Calvé

2019

Sensors

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Several gas molecules of environmental and domestic significance exhibit a strong deep-UV absorption. Therefore, a sensitive and a selective gas detector based on this unique molecular property (i.e., absorption at a specific wavelength) can be developed using deep-UV absorption spectrophotometry. UV absorption spectrometry provides a highly sensitive, reliable, self-referenced, and selective approach for gas sensing. This review article addresses the recent progress in the application of deep-UV absorption for gas sensing owing to its inherent features and tremendous potentials. Applications, advancements, and challenges related to UV emission sources, gas cells, and UV photodetectors are assessed and compared. We present the relevant theoretical aspects and challenges associated with the development of portable sensitive spectrophotometer. Finally, the applications of UV absorption spectrometry for ozone, NO2, SO2, and aromatic organic compounds during the last decades are discussed and compared. A portable UV absorption spectrophotometer can be developed by using LEDs, hollow core waveguides (HCW), and UV photodetectors (i.e., photodiodes). LED provides a portable UV emission source with low power input, low-intensity drifts, low cost, and ease of alignment. It is a quasi-chromatic UV source and covers the absorption band of molecules without optical filters for absorbance measurement of a target analyte. HCWs can be applied as a miniature gas cell for guiding UV radiation for measurement of low gas concentrations. Photodiodes, on the other hand, offer a portable UV photodetector with excellent spectral selectivity with visible rejection, minimal dark current, linearity, and resistance against UV-aging.

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Origins of Parasitic Emissions from 353 nm AlGaN-based Ultraviolet Light Emitting Diodes over SiC Substrates

Cited by 20 publications

References 27 publications

Analysis of the Thickness Effect of Undoped Electron-Blocking Layer in Ultraviolet LEDs

Analysis of the Thickness Effect of Undoped Electron-Blocking Layer in Ultraviolet LEDs

Improved performance of near-ultraviolet InGaN/AlGaN LEDs with various insertion structures

Gas Detection Using Portable Deep-UV Absorption Spectrophotometry: A Review

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