ZnSe-based white LEDs

Kawasaki, Koji; Matsubara, Hideaki; Nakanishi, Futoshi; Nakamura, Toshio; Doi, H.; Saegusa, Akihiko; Mitsui, T.; Matsuoka, Takashi; Irikura, Motoki; Takebe, Toshihiko; Nishine, Shiro; Shirakawa, T.

doi:10.1016/s0022-0248(00)00275-x

Cited by 82 publications

(44 citation statements)

References 7 publications

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“…It has useful electronic properties such as a wide and direct bandgap, low electrical resistivity and n-type conductivity. The important optical properties such as broad transparency from visible to mid infrared (MIR) wavelengths, high refractive index, low dispersion and high photosensitivity combined with electronic properties have been exploited in many optoelectronic devices such as LEDs, laser diodes, MIR sources, solar cells [1][2][3][4][5] and optical windows, lenses and prisms. Low-loss waveguides have been realized in ZnSe substrates by methods such as diamond dicing [6], laser writing [7], proton implantation [8] and a macroscopic Fourier transform infrared-attenuated total reflection (FTIR-ATR) waveguide element has been used for the detection of DNA hybridization [9].…”

Section: Introductionmentioning

confidence: 99%

Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications

Mittal¹,

Sessions²,

Wilkinson³

et al. 2017

Opt. Mater. Express

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Zinc Selenide (ZnSe) is a promising mid-infrared waveguide material with high refractive index and wide transparency. Optical quality ZnSe thin films were deposited on silicon substrates by RF sputtering and thermal evaporation, and characterized and compared for material and optical properties. Evaporated films were found to be denser and smoother than sputtered films. Rib waveguides were fabricated from these films and evaporated films exhibited losses as low as 0.6 dB/cm at wavelengths between 2.5 µm and 3.7 µm. The films were also used as isolation/lower cladding layers on Si with GeTe 4 as the waveguide core and propagation losses were determined in this wavelength range.

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Section: Introductionmentioning

confidence: 99%

Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications

Mittal¹,

Sessions²,

Wilkinson³

et al. 2017

Opt. Mater. Express

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“…2 Typical electroluminescence spectrum of a ZnSe-based white LED grown on conductive n-type ZnSe substrate. 1 The power efficiency which is 9.5 % is calculated by using the typical rated values of bright InGaN-based white (blue-yellow system) LED and its spectrum. The rated values are 3.6 V, 20 mA and 28 lm/W.…”

Section: Optical Electrical and Color Characteristics Of Znse-based mentioning

confidence: 99%

“…This value is approximately 1 V lower than that of the InGaN-based LEDs in principle. This result leads to the advantage of power efficiency, that of the ZnSe-based one will be higher than that of the GaN-based one if their luminous efficiencies are equal.The group of Sumitomo Electric Industries have developed the ZnSe-based white LEDs for the application as the back light source of the LCDs [1,2]. The devices utilize a phenomenon unique to ZnSe homo-epitaxial structures grown on conductive n-type ZnSe substrates.…”

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confidence: 99%

Slow mode degradation mechanism of ZnSe based white LEDs

Adachi

Ando

Abe

et al. 2004

Physica Status Solidi (b)

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PACS 71.55. Gs, 72.20.Jv, 78.55Et, 81.05.Dz, 81.15.Hi, 85.60.Jb This paper presents slow mode degradation mechanism of ZnSe-based white LEDs, which is induced by point defect. The white LEDs are very high quality devices, of which the optical power at a forward current of 20 mA is 8.3 mW and the luminous efficiency is 28 lm/W, which is comparable to GaN-based white LEDs in the market. It is proven that microscopic point defects in the devices, detected as deep hole traps of the H1 center (E v + 0.6 eV) and H0 center (E v + 0.8 eV) in p-type ZnMgSSe cladding layer, are responsible for the slow-mode degradation. These point defects, related to nitrogen complex centers, are very electrically active under device operation. An important insight of the H0 center are found that the mobility of the defect is extremely high, and then it induces marked interaction with macroscopic defects. IntroductionThe recent commercialization of InGaN-based white light emitting diodes (LEDs) has led to wide spread expectations for their potential applications in areas such as general purpose indication, back light for liquid crystal displays (LCDs) and plug-in replacements for incandescent lamps. The next generation of mobile full-color displays such as a cellular phone will require white LEDs with low power consumption. ZnSe-based white LEDs have several attractive advantages compared to the InGaN-based one. One of the significant advantages is the operating voltage, which is about 2.7V. This value is approximately 1 V lower than that of the InGaN-based LEDs in principle. This result leads to the advantage of power efficiency, that of the ZnSe-based one will be higher than that of the GaN-based one if their luminous efficiencies are equal.The group of Sumitomo Electric Industries have developed the ZnSe-based white LEDs for the application as the back light source of the LCDs [1,2]. The devices utilize a phenomenon unique to ZnSe homo-epitaxial structures grown on conductive n-type ZnSe substrates. A portion of the main greenishblue emission from the ZnCdSe active layer of a pn junction diode is absorbed by the conductive n-ZnSe substrate, which in turn gives off a strong broad yellow emission centered on 585 nm due to the excitation to so-called self-activated center. These two emission bands combine to give a spectrum, which appears white color to the naked eye. This phenomenon was found during the development of ZnSe-based blue laser diodes [3,4]. Wenish et al. also reported the broadband orange emission centered on 600 nm when the conductive ZnSe substrate is excited with the light of photon energy lower than the ZnSe band-gap energy [5].The present white LEDs have several advantages in practical use. One is the low operating voltage ∼2.7 V as described above. And another one is the small scattering of color tone and a large portion of the white

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“…For example, full color LED emission has been demonstrated with ZnCdSe/ZnCdMgSe pseudomorphic QWs grown on InP [2]; CdZnSSe quaternary alloys have been used to produce laser emission in the 2.48 to 2.21 eV range (bluish green to greenish yellow) by varying the Cd content to values even higher than 40% [3]; red to green emission (1.94 to 2.41 eV), has been obtained with ZnSe/BeTe type-II LEDs through spatially indirect transitions [4]. LEDs with apparent white emission to the naked eye have been produced from homoepitaxial grown ZnSe pn heterostructures [5]. Since CdTe/ZnTe and CdSe/ZnSe QWs could be tuned, in principle, from the infrared to the green and to the blue, respectively, the approach that we present in this work is to cover the full red-blue range employing a combination of CdTe/ZnTe and CdSe/ZnSe QWs.…”

Section: Introductionmentioning

confidence: 99%

Growth and characterization of ultra‐thin quantum wells of II–VI semiconductors for optoelectronic applications

Hernández‐Calderón

García‐Rocha

Dı́az-Arencibia

2004

Physica Status Solidi (b)

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Atomic layer epitaxy (ALE) was used to grow CdTe and CdSe quantum wells (QWs) with 1 to 4 monolayer thickness. With this ultra-thin quantum wells (UTQWs) it is possible to cover the red-blue spectral range. Low temperature photoluminescence spectroscopy reveals that most of these UTQWs present very intense and narrow emission and, depending on growth conditions, no thickness fluctuations are observed over the whole sample area. The heterostructures were grown at different temperatures between 260 and 290 °C. Both CdTe and CdSe UTQWs grown at the higher temperature presented blue-shifted emission compared to those grown at lower temperatures. This effect is attributed to Cd losses by reevaporation and Cd substitution by Zn. This effect of the temperature can be employed for fine tuning of the UTQW emission. The critical thickness of CdSe/ZnSe grown by ALE is estimated to be 5 ML. 1 Introduction After the first blue-green laser diode, produced in 1991 from wide-band-gap II-VI semiconductors [1], many efforts have been addressed to improve their lifetime and spectral range; it is desirable to produce full color emission devices based on II-VI semiconductors. Zn 1-x Cd x Se/ZnSe quantum wells (QWs) with x < 0.25 and thickness of a few nm have been employed as the active region of blue-green LEDs and lasers grown on GaAs substrates. To extend the emission range towards lower energies, ternary alloys with a higher Cd content are required. However, the increase of Cd in the QW increases the lattice mismatch with the ZnSe barrier, the consequence is that strain and alloy disorder produce the degradation of the optical and structural properties of the QWs. In order to overcome these difficulties a broader range of materials have been employed. For example, full color LED emission has been demonstrated with ZnCdSe/ZnCdMgSe pseudomorphic QWs grown on InP [2]; CdZnSSe quaternary alloys have been used to produce laser emission in the 2.48 to 2.21 eV range (bluish green to green-

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ZnSe-based white LEDs

Cited by 82 publications

References 7 publications

Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications

Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications

Slow mode degradation mechanism of ZnSe based white LEDs

Growth and characterization of ultra‐thin quantum wells of II–VI semiconductors for optoelectronic applications

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