Enhancement in emission efficiency of diamond deep-ultraviolet light emitting diode

Makino, Toshiharu; Yoshino, Kiyoshi; Sakai, Norihiro; Uchida, Kouji; Koizumi, Satoshi; Kato, Hiromitsu; Takeuchi, Daisuke; Ogura, Masahiko; Oyama, Kazuhiro; Matsumoto, Tetsuya; Okushi, Hideyo; Yamasaki, Satoshi

doi:10.1063/1.3625943

Cited by 75 publications

(63 citation statements)

References 15 publications

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“…The density dependent diffusion coefficient D(N) was given by Eqs. (1) and (2). The finite size of the grating was not taken into account (the diffracted beam spot size was much smaller than the excited region).…”

Section: Appendix: Theory Of Transient Diffraction At the Grating Crementioning

confidence: 99%

“…1 Introduction Diamond has extreme physical properties which predispose it to applications in optoelectronics and X-ray, UV, and particle detector physics and also the light-emitting UV diode based on diamond was proposed [1,2]. The detailed knowledge of carrier transport and recombination on picosecond and nanosecond time scales has crucial importance for further evolution of new diamondbased devices.…”

mentioning

confidence: 99%

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Optical study of carrier diffusion and recombination in CVD diamond

Kozák

Trojánek

Malý

2013

Physica Status Solidi (a)

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We report on the measurements of nonequilibrium carrier dynamics in monocrystalline diamond prepared by the chemical vapor deposition (CVD) technique. Nonlinearly excited laser-induced transient grating (LITG) and timeresolved photoluminescence (PL) were used for investigation of carrier diffusion and recombination. Diffusion constant was observed to be strongly dependent on the sample temperature and carrier density (D ¼ 2.5-35 cm 2 s À1 ) what was explained in terms of the density dependent carrier-carrier scattering. The new method based on the time-resolved PL was proposed for measuring the diffusion and recombination dynamics of excitons. The measured exciton lifetime t FE ¼ 700-800 ns was temperature independent between 100 and 295 K.

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Section: Appendix: Theory Of Transient Diffraction At the Grating Crementioning

confidence: 99%

mentioning

confidence: 99%

Optical study of carrier diffusion and recombination in CVD diamond

Kozák

Trojánek

Malý

2013

Physica Status Solidi (a)

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“…Because diamond, like Ge and Si, is an indirect-bandgap semiconductor, its light emission per se is unlikely to be very efficient; however, its large exciton binding energy has enabled room-temperature UV emission from pin diodes. [114] The key defect-center property of diamond is its notable N-V and Si-V defect centers with their long spin-relaxation times. These defect centers show promise for use in quantum information and communication (single photon source) applications, and have now been incorporated in diamond devices in which applied voltages can change the charge state of the center.…”

Section: Diamondmentioning

confidence: 99%

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

Tsao

Chowdhury

Hollis

et al. 2017

Adv Elect Materials

902

437

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“…Diamond on the other hand is a indirect band-gap semiconductor. Even so, diamond-based deep UV LEDs have been demonstrated, but with a relative low efficiency [6]. The AlGaN and AlInN alloys are the only alloy systems with direct and tunable band-gap in the UV region.…”

Section: Introductionmentioning

confidence: 99%

“…At that time, both the n-and p-type conductivity was very poor and the doping is still today one of the most challenging issues in this field in order to achieve high-performance devices. [6].…”

Section: Introductionmentioning

confidence: 99%

Doping of high-Al-content AlGaN grown by MOCVD

Nilsson¹

2014

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The high-Al-content Al x Ga 1-x N, x > 0.70, is the principal wide-band-gap alloy system to enable the development of light-emitting diodes operating at the short wavelengths in the deep-ultraviolet, λ < 280 nm. The development of the deep-ultraviolet light-emitting diodes (DUV LEDs) is driven by the social and market impact expected from their implementation in portable units for water/surface disinfection and based on the damaging effect of the deep-ultraviolet radiation on the DNA of various microorganisms. Internationally, intense research and technology developments occur in the past few years, yet, the external quantum efficiency of the DUV LEDs is typically below 1%.One of the main material issues in the development of the DUV LEDs is the achievement of n-and ptype high-Al-content Al x Ga 1-x N layers with low resistivity, which is required for the electrical pumping of the diodes. The doping process becomes significantly more complex with increasing the Al content and the electrical resistivity is as high as 10 1 -10 2 Ω . cm for n-type AlN doped by silicon, and 10 7 -10 8 Ω cm for p-type AlN doped by magnesium.The present study was therefore focused on gaining a better understanding of the constraints in the doping process of the high-Al-content Al x Ga 1-x N alloys, involving mainly silicon. For this purpose, the epitaxial growth of the high-Al-content Al x Ga 1-x N and AlN by implementing the distinct hot-wall MOCVD was developed in order to achieve layers of good structural and morphological properties, and with low content of residual impurities, particularly oxygen and carbon. Substitutional point defects O N and C N may have a profound impact on the doping by their involvement in effects of ntype carrier compensation. The process temperature was varied between 1000 and up to 1400 °C, which is a principal advantage in order to optimize the material properties of the high-Al-content Al x Ga 1-x N and AlN. The epitaxial growth of the high-Al-content Al x Ga 1-x N and AlN was largely performed on 4H-SiC substrates motivated by (i) the lattice mismatch of ~ 1% along the basal plane (the smallest among other available substrates including Si and sapphire), (ii) the good thermal conductivity of 3.7 W cm -1 K -1 , which is essential to minimize the self-heating during the operation of any light-emitting diode, and (iii) the limited access to true-bulk AlN wafers. The outcome of this study is accordingly summarized and presents our understanding for (i) the complex impact of silicon and oxygen on the n-type conductivity of Al 0.77 Ga 0.23 N, representative for the alloy composition at which a drastic reduction of the n-type conductivity of Al x Ga 1-x N is commonly reported (paper 1); (ii) the strain and morphology compliance during the intentional iv doping by silicon and magnesium, and its correlation with the resistivity of highly doped layers of Al 0.82 Ga 0.18 N alloy composition (paper2); (iii) the n-type conductivity of highly Si-doped Al 0.72 Ga 0.28 N as bound by the process temperature (p...

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Enhancement in emission efficiency of diamond deep-ultraviolet light emitting diode

Cited by 75 publications

References 15 publications

Optical study of carrier diffusion and recombination in CVD diamond

Optical study of carrier diffusion and recombination in CVD diamond

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

Doping of high-Al-content AlGaN grown by MOCVD

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