Yung-Sheng Liu

Yung-Sheng Liu
National Tsing Hua University | NTHU · Institute of Photonics Technologies

PhD

About

94
Publications
4,678
Reads
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1,649
Citations
Introduction
Yung-Sheng Liu, currently Distinguished Professor Emeritus, worked previously as Director at the Institute of Photonics Technologies, National Tsing Hua University, and Optotoelectronics & System Labs, ITRI in Taiwan. Yung-Sheng does research in Optical Engineering, Optics and Materials Science. Their project, funded by the 'Ministry of Science and Technology" on Silicon Photonics, engaged in the development of integrated photonics for optical interconnects, sensing and communication.
Additional affiliations
August 2006 - February 2015
National Tsing Hua University
Position
  • Director & Macronix Chair Professor
August 2006 - February 2015
National Tsing Hua University
Position
  • Macronix Chair Professor (Professor Emeritus)
February 2000 - February 2006
University System of Taiwan (UST)
Position
  • Vice Chancellor
Description
  • UST consists of four leading research universities in Taiwan including National Tsing Hua University, National Chiao Tung University, National Central University and National Yang Ming University with total students over 40,000.

Publications

Publications (94)
Article
We investigated the near infrared enhancement in Cu(In,Ga)Se(2) (CIGS)- based solar cells utilizing a hydrogen-doping ZnO (ZnO:H) window layer. The results show that the carrier concentration of ZnO:H film is lower than that of AZO film which can increase the transmittance in the NIR. The advantage of ZnO:H film is higher Hall mobility than AZO fil...
Conference Paper
A cost-effective process using self-aligned microbonded Ge-beams on silicon waveguides is presented. Heterojunction photodetectors featuring low dark-current of 0.7uA (-2V) and high turn-on current of 10.8 mA (+3V) are demonstrated. The operation bandwidth is 11-16GHz.
Article
In this study, a novel structure using a sandwiched CuGa/CuInGa/In precursor layer is employed for improving the Voc and Jsc of a CIGS solar cell. The addition of a CuGa layer on the surface of CuInGa precursor enhanced the Ga concentration in the space charge region and thus enhanced the Voc by about 18.2%. The addition of an In layer to the botto...
Conference Paper
We report a silicon avalanche photodetector with low breakdown voltage of -6.44V. Through a design of narrow interdigitated junction spacing and Ni-silicide process, a high avalanche gain of 30 and low dark current are achieved.
Article
The growth of grain size of CuInGaSe2 and the Ga distribution in the thin film CuInGaSe2 solar cell devices fabricated using a sputtering CuInGa ternary target have been studied. It was observed, adding a thin CuGa layer on top of the surface of CuInGa ternary precursor would increase the Ga concentration, and thus the energy gap in the space-charg...
Article
Rapid oxidation in silicon induced by nanosecond UV laser pulses has been recently reported [1]. A significant amount of oxygen was observed to be incorporated in theregrown silicon layer when irradiation took place in air or in oxygen ambient. The fundamental interaction and transport kinetics involved include: incorporation of impurity during sur...
Article
Characteristics of CW Ar-ion laser annealed InSb has been studied; properties include stoichiometric composition analysis and electrical C-V measurements. The stoichiometry compositions of laser-annealed samples at different power levels and scan speeds have been studied using an electron microprobe technique. Results were compared with electrical...
Chapter
This chapter reviews briefly the major development of light sources including incandescence light, fluorescence light, lasers, particularly, the semiconductor laser and high-brightness blue/white GaN-based LED. It shows that the nano-science, in a broader sense, has played a critical role in the subsequent commercialization of these great invention...
Conference Paper
Major breakthroughs that took place chronically in the light source development are: the invention of incandescence light bulbs, the invention of lasers, particularly semiconductor lasers, and the high-brightness blue/white LED. Two of these represent the major advances in the lighting technologies. It is further shown that what we called "nano-sci...
Conference Paper
Full-text available
With the fast expansion of Internet usage, the demand of 10 Gb/s transmission optoelectronic devices for local-area-network (LAN) and storage-area-network (SAN) is increasing. The key issues of these applications are to improve the cost, manufacturability, and reliability of optoelectronic devices in high speed access transmission. The authors demo...
Article
Full-text available
This paper reviews the current status of the solid state lighting technology development at the Opto-Electronics & Systems Labs. (OES), Industrial Technology Research Institute (ITRI) and recent industrial activities in the related areas in Taiwan.
Article
Full-text available
This second conference on Input/Output and Imaging Technologies, part of the International Optoelectronics Symposium Held in Taipei, Taiwan on 26-28 July 2000 in conjunction with Photonics Taiwan 2000. This year's conference themes are: 3D object representation and vision-based applications, output devices and imaging, digital camera design and app...
Article
Full-text available
A fully embedded board-level guided-wave optical interconnection is presented to solve the packaging compatibility problem. All elements involved in providing high-speed optical communications within one board are demonstrated. Experimental results on a 12-channel linear array of thin-film polyimide waveguides, vertical-cavity surface-emitting lase...
Conference Paper
Full-text available
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Cray T-90 machine
Conference Paper
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Gray T-90 machine. A waveguide propagation loss of 0.21...
Article
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Cray T-90 machine. A waveguide propagation loss of 0.21...
Conference Paper
The technical approach and progress achieved under the Polymer Optical Interconnect Technology (POINT) program are described in this paper. The POINT program is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University, and University of California at San Diego (UCSD), sponsored by DARPA/ETO, to develop affordable optoelect...
Article
Full-text available
The technical approach and progress achieved under the Polymer Optical Interconnect Technology (POINT) program are described in this paper. The POINT program is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University, and University of California at San Diego (UCSD), sponsored by DARPA/ETO, to develop affordable optoelect...
Article
The development of optical interconnect technology using fiber optics in the 1970s was a cornerstone of the modern telecommunication industry. Replacing copper cables with optical fibers provides superior performance in terms of wide data bandwidths, reduced noise, and low loss. It also significantly reduces the cost of communication in terms of do...
Article
Data link components are demonstrated based on 850 nm vertical cavity lasers (VCSELs) and short wavelength GaAs PIN detectors. These components are the foundation of an array data link solution set and offer easy incorporation with traditional multimode fiber based backplanes, or polymer waveguide based backplanes
Conference Paper
Due to the explosive growth in high speed network communication and the rapid advance in the processor speed and processing power, data transfer bandwidths between chips, modules, board, backplane and cabinets have increased drastically. The required interconnect bandwidths for efficient data communication across different platforms have increased...
Conference Paper
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Cray T-90 machine. A waveguide propagation loss of 0.21...
Conference Paper
This paper describes the technical approach and progresses of the POINT (Polymer Optical Interconnect Technology) program. This project is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego (UCSD), sponsored by DARPA/ETO to develop affordable optoelectronic packaging and inte...
Article
This paper describes the technical approach and progresses of the POINT program. This project is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego, sponsored by DARPA/ETO to develop affordable optoelectronic packaging and interconnect technologies for board and backplane app...
Article
The development of multimode passive polymer optical waveguide components for board and backplane interconnect applications, such as in the DARPA-sponsored, polymer optical interconnect technology (POINT) program, require several optics design issues to be addressed including efficiency and modal noise. For example, the mating of arrays of sources,...
Article
The design and architecture of bi-directional optical backplanes with single and multiple bus lines for high performance bus are reviewed and bus systems with one and 2-bus lines at a wavelength of 850 nm are experimentally demonstrated. For optical backplanes with single-bus line, a speed of 1.2 Gbit/sec at a wavelength of 1,3 μm is demonstrated....
Conference Paper
Full-text available
The architecture of a hybrid electrical and optical backplane with multiple bus lines for high performance bus is proposed and bus systems with 2-bus lines at a wavelength of 850 nm are experimentally demonstrated, with a size of collimation lens (here we used graded index (GRIN) lenses) and level of collimation-limited separation of 1.5 mm between...
Conference Paper
The Polymer Optical interconnect Technology (POINT) is a collaborative program among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego (UCSD), sponsored by ARPA, in developing affordable optoelectronic packaging and interconnect technologies for board- and backplane-level optical interconnect applicatio...
Article
Both multichip modules (MCMs) and optical interconnects are expected to play a pivotal role in the development of high performance electronic systems. Only by packaging optoelectronic components within the multichip modules can the advantages of both technologies be realized. We have demonstrated the incorporation of optoelectronic components into...
Conference Paper
In this paper, we describe an effort in developing low-cost optoelectronic packaging and interconnect technologies for board-level optical interconnect applications. Specifically, our work includes (a) hybrid packaging of electrical and optical components, e.g., vertical-cavity surface-emitting-laser (VCSEL) devices using a thin-film embedded-chip...
Article
Recent advances in optical devices, polymeric materials, and in the electronic MCM packaging and interconnect technologies could bring the cost of optical interconnect to a level affordable for module, board, and backplane level interconnect applications. Specifically, we discuss how the development in (1) vertical-cavity surface-emitting-laser dev...
Article
Optical backplanes are of increasing interest for commercial and military avionic processors, and for commercial supercomputers. Projected interconnection density limits of electrical interconnects are rapidly becoming a bottleneck, preventing optimal exploitation of electronic processor capability. A potential obstacle to the commercial developmen...
Article
Fabrication of micro-vias with a diameter of less than 100 μm in polymeric materials is a key processing technology for high-density interconnect applications. This paper discusses material properties that are relevant to laser ablation and describes several laser techniques (e.g. excimer, UV YAG and CW argon ions lasers) for micro-via fabrication...
Article
SiC photodiodes were fabricated using 6 H single-crystal wafers. These devices have excellent UV responsivity characteristics and very low dark current even at elevated temperatures. The reproducibility is excellent and the characteristics agree with theoretical calculations for different device designs. The advantages of these diodes are that they...
Article
Full-text available
In this paper, we describe a novel approach for fabrication of low-cost optoelectronic modules for optical interconnect applications. The concept includes: (1) placement of optical and electrical components on a common substrate using a chip-first MCM structure to improve thermal handling capabilities, (2) fabrication of both optical and electrical...
Article
Citation Y. S. LIU, "Laser Metal Deposition for High-Density Interconnect," Optics & Photonics News 3(6), 10-14 (1992) http://www.opticsinfobase.org/opn/abstract.cfm?URI=opn-3-6-10
Article
The overall objective of this program has been to investigate laser- activated chemistry for fabrication of metal lines on low dielectric constant substrates. The need to provide highly conductive metal on polymeric substrates (with epsilon < 3.5) is essential for high-speed interconnect technology. Using lasers to fabricate these interconnects off...
Article
This paper describes a novel excimer laser beam delivery method for surface sculpting using a binary mask approach. This technique is useful for profiling a surface into arbitrary shapes and geometries with a high laser energy delivery efficiency. The binary mask technique is particularly attractive for deliver of a pulsed laser such as excimer las...
Article
The optical properties of polyetherimide resin as described by the complex index of refraction, N = n - ik, are derived by Kramers-Kronig analysis of experimental absorption and reflectance data obtained in the range 40 μm ≥ λ ≥105 nm. Potential uses of this polymer as a printed circuit board material and as a packaging medium for microelectronic c...
Article
A new formula is presented for the etch depth l per pulse of an excimer laser of fluence F. Incremental ablation is defined as the etch depth per pulse after many pulses. We show that l is proportional to F, rather than ln(F).
Article
This paper reviews several laser-based area-selective processing techniques developed for high-density multichip interconnection applications. Key material and process requirements for the development of a viable laser-direct-write interconnect technique on polyimide are addressed. How to Cite This Article Link to This Abstract Blog This Article...
Article
The interest in laser processing technology has increased significantly in recent years because of increasing demands for application-specific IC design and fabrication, yield enhancement, circuit restructuring, and prototyping; all of these benefit from an adaptive processing technique using direct energy for improvement of precision, resolution,...
Article
Laser irradiation of organometallic palladium compounds with an argon ion laser at 351 nm is used to selectively deposit catalytic amounts of palladium on polyimide. Subsequent immersion of the irradiated samples in an electroless copper solution results in copper deposition. Since a few monolayers of palladium are sufficient to catalyze the electr...
Article
Full-text available
Selective modification of surface reactivities with lasers, using either direct writing or projection method, is intrinsically a sensitive method to prepare a surface for highresolution and high-speed area selective thin film deposition. In this paper, we demonstrated the use of laser direct-writing and projection patterning techniques for selectiv...
Article
Interactions of high photon energy (hν≳5 eV) radiation from an excimer laser with polymeric materials has been studied. Photo‐etching rates at both 193 nm and 248 nm were measured. These results, considered together with our recent measurements of the VUV optical properties of these polymers, give new insights into the mechanisms of the ablative p...
Conference Paper
Photoetching with excimer lasers has been studied in a variety of polymeric materials. Photoetching rates of polymers irradiated were measured at various laser wavelengths and fluences. The relationship of these results to the polymer absorption coefficient is examined. We propose that different mechanisms of photoetching may prevail, which depend...
Article
The optical properties of bisphenol-A polycarbonate resin as described by the complex index of refraction, N = n – ik, are derived by Kramers-Kronig analysis of experimental absorption and reflectance data obtained in the range 40μm ≥ λ ≥ 105 nm. Electronic absorption processes in polycarbonate are characterized by two broad absorption peaks center...
Article
X‐ray photoelectron spectroscopy (XPS) has been used to study the surface composition of poly(methylmethacrylate) (PMMA) and poly(α‐methylstyrene) (α‐MePS) following excimer laser irradiation at 193 nm. For fluence levels between 50 and 300 mJ/cm<sup>2</sup>, no surface compositional changes were observed after irradiation of PMMA. However, α‐MePS...
Article
Full-text available
Absorption coefficients for some technologically important polymer materials are given in the wavelength range ∼240–170 nm. Absorption coefficients at 193 nm for these polymers show a wide range of values from ∼2×10<sup>2</sup> cm<sup>-</sup><sup>1</sup> for polytetrafluoroethylene (Teflon) to ∼4×10<sup>5</sup> cm<sup>-</sup><sup>1</sup> for polyim...
Article
Full-text available
Mixtures of poly(methyl methacrylate) and poly(α‐methyl styrene) were prepared and their optical absorption coefficients at 193 nm were measured. A study of photoetching rate of these polymeric materials using an ArF excimer laser at 193 nm shows two regions of distinctly different etching characteristics. At relatively high fluences (>300 mJ/cm2)...
Article
Laser photoetching of polymers has been shown to be a useful method of producing via holes or patterns and is of potential importance in microelectronics fabrication. The maskless, self-developing nature of the process also offers unique opportunities in the preparation of packaging assemblies. Etching of via holes at any discretionary site for mul...
Article
The feasibility of high speed direct writing of high resolution structures using a laser beam was demonstrated. Tungsten was selectively deposited on silicon via surface reduction reaction of tungsten hexafluoride. Fine lines of micron dimension with smooth surface morphology were fabricated using an argon laser at a writing speed of several cm per...
Article
Potassium titanyl phosphate (KTP) offers very attractive physical properties for optical second-harmonic generation. Its future as a complement to Nd:YAG in both pulsed and CW applications appears bright. This article concentrates on KTP growth, physical properties, performance, and applications in second-harmonic generation. The information here i...
Article
Full-text available
The Raman spectrum of tungsten silicide has been observed and is reported for the first time. It was obtained on the MOLE Raman microprobe during the examination of an annealed sample of tungsten deposited over crystalline silicon. A similar examination of fine tungsten lines, 8 μm wide by 20 nm thick, selectively deposited on a crystalline silicon...
Article
Advances in solid-state, slab-geometry lasers and their application to the development of laser sources tunable across the UV and IR spectral range and operable at a high-average-power level are discussed. A slab-type laser configuration is manufactured as a rectangular cross-section slab with plane parallel surfaces; the slab is simultaneously pum...
Article
We have demonstrated high-average-power second-harmonic generation with an output power of 5.6 W at 532 nm by intracavity frequency doubling using Type II KTiOPO(4) in a Nd:YAG laser oscillator acousto-optically Q switched at 5 kHz.(1) The average power achieved, limited only by the power-supply current available in these experiments, was about thr...
Article
MOSFET's were fabricated in laser-recrystallized silicon islands on fused quartz substrates using a standard n-channel self-registered poly-gate process. Selective absorption obtained with patterned dielectric films was used to control the shape of the melt front during recrystallization of patterned LPCVD polysilicon islands. IR imaging of the las...
Conference Paper
Two fundamental problems hinder wider use of solid-state IR lasers, such as Nd:YAG for generating high-power visible radiation over several watts: (1) thermal-optical problems degrade the beam brightness in a rod-type solid-state laser operated at a high-power level; (2) nonlinear optical materials useful as an efficient frequency doubler for highp...
Article
Full-text available
This paper describes the characterization of residual defects using transient capacitance spectroscopy for ion‐implanted Si annealed with a Q‐switched Nd‐glass laser. The deep‐level defect levels observed in this study were similar to those obtained in low‐fluence ion implanted samples. The spatial distributions of deep‐level defect concentrations...
Conference Paper
Since the first reported work of developing the self-injection technique in solid-state YAG and dye lasers1,2 for generating high-energy pulses in the nanosecond range, several other groups have further demonstrated the usefulness of this technique to other kinds of lasers such as f iashlamp pumped dye lasers and unstable YAG oscillators.3,4 The pr...
Conference Paper
The characteristics of MOSFET's fabricated in laser-recrystallized silicon islands on amorphous substrates using a standard n-channel poly-gate process were studied. Selective absorption using patterned dielectric films and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging o...
Article
Selective absorption, using patterned dielectric films, and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging of the laser heated region was used to optimize and control the recrystallization. MOSFETs were fabricated in laser-recrystallized silicon islands on amorphous subst...
Article
Q‐switched laser irradiation has been used to anneal O<sup>+</sup>‐implanted silicon to form SiO 2 layers. Results of differential Fourier‐transformed infrared spectroscopy and transmission electron microscopy confirm the formation of oxide layers. Segregation of oxygen toward the surface was observed by secondary ion mass spectroscopy and correlat...
Article
Amorphous silicon has been produced on a single‐crystal silicon surface that was exposed to intense pulsed UV‐laser radiation at 266 nm. In addition, the formation of an oxide several tens of nanometers in thickness is observed when the irradiation takes place in an O 2 or in an air ambient. Various experimental techniques including transmission el...
Conference Paper
KTP (KTiOPO4) is a new class of nonlinear optical crystal which has been recently developed. The crystal exhibits several unique and interesting properties including a high nonlinear coefficient (comparable with that of Ba2NaNb5O15), a high damage threshold, and a low degree of sensitivity to the thermally induced phase-mismatch. In the present wor...
Conference Paper
Rapid Oxidation of the amorphous silicon layer induced by pulsed UV laser irradiation is reported. The oxide of ~400 Å was produced when a silicon sample was irradiated by intense UV laser pulses in an air or an oxygen ambient. (The oxide thickness shall be compared with the native oxide thickness of ~10 Å for an unirradiated sample.) The formation...
Article
Amorphous silicon has been produced on a single crystalline silicon surface by intense UV laser radiation at 266 nm followed by rapid quenching. In addition, formation of oxide of several tens of nanometers has been observed when irradiation takes place in air or in O2 ambient. Various experimental techniques including Transmission Electron Microsc...
Article
The application of an intracavity-injecting technique to a Q-switched Nd:YAG oscillator for efficiently generating high-power nanosecond pulses is described. Nanosecond pulses produced are synchronizable, reproducible, and remarkably stable. Applications of the technique to other types of lasers are discussed.
Article
This paper describes a study comparing the results of the electrical measurements and the regrowth behavior of ion‐implanted silicon annealed with an 80‐ns (FWHM) laser pulse at 1.06 μm. Certain correlations were established among the threshold energy density required for melting, the dopant distributions, and the diode junction depth and leakage....
Article
By probing transient optical reflectivity, we have investigated the liquid phase epitaxial regrowth kinetics of ion‐implanted silicon during laser annealing. For annealing of ion‐implanted silicon with an 80‐ns (FWHM) pulse of various intensities at 1.06 μm, the threshold energy density required for melting is observed to be a constant. Above this...
Article
This paper describes measurements of electrical properties and the regrowth behavior of ion-implanted silicon annealed with an 80-ns (FWHM) laser pulse at 1.06 μm. The experimental results include: (1) a determination of threshold energy density required for melting using a transient optical reflectivity technique, (2) measurements of dopant distri...
Article
Full-text available
The observation of regenerative oscillation in a laser-pumped dye laser is reported. Pulse trains of 1-nsec pulses have been observed from a rhodamine 6G dye laser pumped with a 50-nsec pulse at 5320 A. The regenerative oscillation is produced by using a novel cavity-flipping technique recently developed. The principle of this technique and experim...
Article
The spectral phase‐matching bandwidths in LiIO 3 , LiNbO 3 , CDA, and KDP (type I and type II) for second harmonic generation (SHG) at 1.06 μm have been accurately measured using a tunable line‐narrowed Nd : glass laser. The present results disagree with previously published data. Mechanisms such as sum‐frequency generation which could contribute t...
Article
We discuss the properties of a Brewster‐angle briefirngent filter (BBF) using inside a laser cavity for line narrowing and tuning of a high‐power low‐gain laser, in particular, a Nd : glass laser. The free‐spectral range (FSR) and t he dispersion function are found to be strongly angle dependent. This tuning method is found to be extremely simple,...
Article
Full-text available
We report high‐efficiency high‐power uv generation at 266 nm by frequency quadrupling of Nd laser using two deuterated KDP crystals. An angle‐tuned type‐II phase‐matched (eoe‐interaction) deuterated KDP crystal is used for doubling 1.064 μm and a temperature‐tuned 90° phase‐matched deuterated KDP crystal is used, for the first time, for doubling 53...
Article
The specific heat of cesium dideuterium arsenate (CsD 2 AsO 4 ) was measured with a scanning differential calorimetric method in the temperature range from 0 to 120 °C. Using a least‐squares curve fit, the power‐series expression of the specific heat in this temperature range is found to be C p (cal g<sup>-</sup><sup>1</sup> deg<sup>-</sup><sup>1</...
Article
Full-text available
The vibrational–vibrational (V–V) energy transfer probability P0,1v,v−1 in CO–CO collisions, CO(0)+CO(v) ↠ CO(1) + CO(v−1), has been measured from the first overtone emission spectra for v=3 to v=9 from vibrationally excited CO&ast; produced in the reaction of oxygen with acetylene at room temperature. Under fast flow conditions in which spontaneou...
Article
Full-text available
The dynamic behavior of a relaxing CO–He mixture has been studied with a computer. The time evolution of the nonequilibrium vibrational population distribution was obtained by numerically integrating the master equations for the vibrational population including vibrational–vibrational (V–V), vibrational–translational (V–T), and spontaneous decay pr...
Article
The frequency response of an amptitude-modulated GaAs luminescence diode has been studied for optical communication application. The modulated light intensity is found to fan off inversely proportional to the modulation frequency over the frequency range ωτ ≳ 1, where τ is the recombinative lifetime. We show that the falloff characteristic is a res...
Article
Full-text available
Application of two-photon selective excitation to isotope separation with high power, high resolution tunable lasers is discussed. A simple kinetic model is given to determine quantum efficiency and separation factor in terms of laser powers and relaxation constants. A numerical example is used to demonstrate the feasibility of the scheme. Results...