Sang Yoon Lee

Bio: Sang Yoon Lee is an academic researcher from Samsung. The author has contributed to research in topics: Thin-film transistor & Layer (electronics). The author has an hindex of 48, co-authored 282 publications receiving 22409 citations. Previous affiliations of Sang Yoon Lee include National Institutes of Health & Kumoh National Institute of Technology.

Large-scale pattern growth of graphene films for stretchable transparent electrodes

Abstract: Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

High-mobility and low-power thin-film transistors based on multilayer MoS2 crystals

Abstract: Unlike graphene, the existence of bandgaps (1–2 eV) in the layered semiconductor molybdenum disulphide, combined with mobility enhancement by dielectric engineering, offers an attractive possibility of using single-layer molybdenum disulphide field-effect transistors in low-power switching devices. However, the complicated process of fabricating single-layer molybdenum disulphide with an additional high-k dielectric layer may significantly limit its compatibility with commercial fabrication. Here we show the first comprehensive investigation of process-friendly multilayer molybdenum disulphide field-effect transistors to demonstrate a compelling case for their applications in thin-film transistors. Our multilayer molybdenum disulphide field-effect transistors exhibited high mobilities (>100 cm2 V−1 s−1), near-ideal subthreshold swings (~70 mV per decade) and robust current saturation over a large voltage window. With simulations based on Shockley's long-channel transistor model and calculations of scattering mechanisms, these results provide potentially important implications in the fabrication of high-resolution large-area displays and further scientific investigation of various physical properties expected in other layered semiconductors. Molybdenum disulphide offers some tantalizing advantages over graphene as a material with which to fabricate field-effect transistors. Kimet al. present a comprehensive study of field-effect transistors made from multilayer samples of MoS2and find that they can achieve high carrier mobilities.

42.2: World's Largest (15‐inch) XGA AMLCD Panel Using IGZO Oxide TFT

Abstract: The world's largest (15-inch) XGA active matrix liquid crystal display (AMLCD) panel made with IGZO TFTs (W/L=29.5/4 μm) was fabricated and evaluated with the field effective mobility of 4.2±0.4 cm2/V-s, Vth of −1.3±1.4V and sub-threshold swing (SS) of 0.96±0.10 V/dec. for a manufacturing-oriented process, the main factors affecting threshold voltage (Vth) of the IGZO thin film transistors (TFT) are investigated. On the glass surface, thicker regions of IGZO film have a negative threshold voltage shift. A dry etching process of molybdenum source and drain (S/D) causes negative shift of the average threshold voltage compared to wet etching in the bottom gate back channel etched TFTs. However, optimization of SiOx passivation and subsequent annealing shift average Vth positively and reduce Vth variation.

Full-colour quantum dot displays fabricated by transfer printing

Abstract: Scientists describe a size-selective quantum dot patterning technique that involves kinetically controlling the nanotransfer process without a solvent. The resulting printed quantum dot films exhibit excellent morphology and a well-ordered quantum dot structure. This technique allows fabrication of a 4-inch (or larger) thin-film transistor display with high colour purity and extremely high resolution.

42.4L: Late‐News Paper: 4 inch QVGA AMOLED Driven by the Threshold Voltage Controlled Amorphous GIZO (Ga2O3‐In2O3‐ZnO) TFT

Abstract: We successfully fabricated GIZO (Ga2O3-In2O3-ZnO) TFTs with high mobility of 2.6 cm2/Vs and threshold voltage standard deviation of 0.7V which is comparable to that of a-Si TFTs. Because conventional 5 mask process and bottom gate TFT structure of back channel etch type with channel length of 5 μm is used, it is expected to be transferred to mass production line in near future. Also we report the dependency of threshold voltage on the post process after the back surface of GIZO is exposed and suggest the effective method for controlling the threshold voltage of amorphous GIZO TFTs. Finally we demonstrate 4 inch QVGA AMOLED display driven by GIZO TFTs.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

Graphene: Status and Prospects

Abstract: Graphene is a wonder material with many superlatives to its name. It is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have zero effective mass, and can travel for micrometers without scattering at room temperature. Graphene can sustain current densities six orders of magnitude higher than that of copper, shows record thermal conductivity and stiffness, is impermeable to gases, and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.

Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils

Abstract: Graphene has been attracting great interest because of its distinctive band structure and physical properties. Today, graphene is limited to small sizes because it is produced mostly by exfoliating graphite. We grew large-area graphene films of the order of centimeters on copper substrates by chemical vapor deposition using methane. The films are predominantly single-layer graphene, with a small percentage (less than 5%) of the area having few layers, and are continuous across copper surface steps and grain boundaries. The low solubility of carbon in copper appears to help make this growth process self-limiting. We also developed graphene film transfer processes to arbitrary substrates, and dual-gated field-effect transistors fabricated on silicon/silicon dioxide substrates showed electron mobilities as high as 4050 square centimeters per volt per second at room temperature.

Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.