Author
Shih-Chang Shei
Bio: Shih-Chang Shei is an academic researcher from National University of Tainan. The author has contributed to research in topics: Light-emitting diode & Wide-bandgap semiconductor. The author has an hindex of 19, co-authored 102 publications receiving 1274 citations.
Papers
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TL;DR: In this article, the optical and electrical properties of indium tin oxide (ITO), Ni(3.5 nm)/ITO(60 nm) and Ni( 5 nm)/Au(5 nm) films were studied, and it was found that the normalized transmittance of ITO and Ni/ITO films could reach 98.2% and 86.6% at 470 nm, respectively.
Abstract: The optical and electrical properties of indium tin oxide (ITO)(60 nm), Ni(3.5 nm)/ITO(60 nm) and Ni(5 nm)/Au(5 nm) films were studied. It was found that the normalized transmittance of ITO and Ni/ITO films could reach 98.2% and 86.6% at 470 nm, which was much larger than that of the Ni/Au film. It was also found that both Ni/ITO and Ni/Au could form good ohmic contact on top of p-GaN. In contrast, ITO on p-GaN was electrically poor and non-ohmic. Nitride-based light-emitting diodes (LEDs) with these three p-contact layers were also fabricated. It was found that the LED forward voltage was 3.65, 3.26 and 3.24 V for the LEDs with ITO, Ni/ITO and Ni/Au p-contact layer, respectively. With a 20 mA current injection, it was also found that measured output power was 7.50, 6.59 and 5.26 mW for the LEDs with ITO, Ni/ITO and Ni/Au p-contact layer, respectively. Although the LED with ITO p-contact could provide the largest output intensity, its lifetime was the shortest due to severe heating effect.
115 citations
TL;DR: In this paper, a nitride-based high-power flip-chip light-emitting diode (LED) with a double-side patterned sapphire substrate (PSS) was proposed and realized.
Abstract: A nitride-based high-power flip-chip (FC) light-emitting diode (LED) with a double-side patterned sapphire substrate (PSS) was proposed and realized. Under 350-mA current injection, it was found that forward voltages were 3.24, 3.26, and 3.25 V for the conventional FC LED, FC LED prepared on PSS, and FC LED with double-side PSS, respectively. It was found that the 350-mA LED output powers were 79.3, 98.1, and 121.5 mW for the conventional FC LED, FC LED prepared on PSS, and FC LED with double-side PSS, respectively. In other words, we can enhance the electroluminescence intensity by 53% without increasing operation voltage of the fabricated LED
81 citations
TL;DR: In this article, GaN epitaxial layers and InGaN/GaN multiquantum well blue light emitting diodes (LEDs) were prepared on both patterned sapphire substrates (PSS) and conventional SApphire substrate.
67 citations
TL;DR: In this paper, the etching behavior of sapphire has been investigated in an inductively couple plasma using Cl2, BCl3 and CH2Cl2 as the reagent.
53 citations
TL;DR: In this paper, a GaN-based light-emitting diode (LED) with nonalloyed metal contacts was demonstrated with non-alloying metal contacts onto the n+-GaN surface and transparent contact layer (indium tin oxide) to serve as the ntype electrode (cathode) and the p-type electrode pad (anode), respectively.
Abstract: In this study, we demonstrate a GaN-based light-emitting diode (LED) with nonalloyed metal contacts onto the n+-GaN surface and transparent contact layer (indium tin oxide) to serve as the n-type electrode (cathode) and the p-type electrode pad (anode), respectively. Comparing with the conventional LEDs, which the electrode pads and/or Ohmic contacts form through conventional Cr∕Au metal contacts, the nonalloyed metal contacts (Ag∕Cr∕Au or Al∕Cr∕Au) used in the present experimental blue LEDs also play the role of reflector to prevent the emitted light from absorption by the opaque electrode pads with low reflectivity (Cr∕Au). With an injection current of 20mA, the enhancement in the light output power has approximately a 14% magnitude compared to the GaN-based LEDs without Ag or Al reflectors under the Cr∕Au electrode pads.
47 citations
Cited by
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TL;DR: Bergh and P.J.Dean as discussed by the authors proposed a light-emitting diode (LEDD) for light-aware Diodes, which was shown to have promising performance.
Abstract: Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.
1,560 citations
TL;DR: This paper provides the groundwork for an understanding of the reliability issues of LEDs across the supply chain and identifies the relationships between failure causes and their associated mechanisms, issues in thermal standardization, and critical areas of investigation and development in LED technology and reliability.
648 citations
TL;DR: This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility.
Abstract: This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...
636 citations
Journal Article•
TL;DR: In this article, a polarization-sensitive optical coherence-domain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample is presented.
Abstract: We present a polarization-sensitive optical coherence-domain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample. The device is insensitive to the rotation of the sample in the plane perpendicular to ranging. Phase measurement accuracy is ±0.86°, but the reflectometer can distinguish local variations in birefringence as small as 0.05° with a distance resolution of 10.8 μm and a dynamic range of 90 dB. Birefringence-sensitive ranging in a wave plate, an electro-optic modulator, and a calf coronary artery is demonstrated.
601 citations