다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

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Spintronics: Fundamentals and applications

Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

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Graphene-based composites

In the past ten years we have witnessed a revival of, and subsequent rapid expansion in, the research on zinc oxide (ZnO) as a semiconductor. Being initially considered as a substrate for GaN and related alloys, the availability of high-quality large bulk single crystals, the strong luminescence demonstrated in optically pumped lasers and the prospects of gaining control over its electrical conductivity have led a large number of groups to turn their research for electronic and photonic devices to ZnO in its own right. The high electron mobility, high thermal conductivity, wide and direct band gap and large exciton binding energy make ZnO suitable for a wide range of devices, including transparent thin-film transistors, photodetectors, light-emitting diodes and laser diodes that operate in the blue and ultraviolet region of the spectrum. In spite of the recent rapid developments, controlling the electrical conductivity of ZnO has remained a major challenge. While a number of research groups have reported achieving p-type ZnO, there are still problems concerning the reproducibility of the results and the stability of the p-type conductivity. Even the cause of the commonly observed unintentional n-type conductivity in as-grown ZnO is still under debate. One approach to address these issues consists of growing high-quality single crystalline bulk and thin films in which the concentrations of impurities and intrinsic defects are controlled. In this review we discuss the status of ZnO as a semiconductor. We first discuss the growth of bulk and epitaxial films, growth conditions and their influence on the incorporation of native defects and impurities. We then present the theory of doping and native defects in ZnO based on density-functional calculations, discussing the stability and electronic structure of native point defects and impurities and their influence on the electrical conductivity and optical properties of ZnO. We pay special attention to the possible causes of the unintentional n-type conductivity, emphasize the role of impurities, critically review the current status of p-type doping and address possible routes to controlling the electrical conductivity in ZnO. Finally, we discuss band-gap engineering using MgZnO and CdZnO alloys.

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Fundamentals of zinc oxide as a semiconductor

Wet chemical etching of single crystal III–V nitrides has proven difficult in the past due to their excellent stability in corrosive liquids. We have found that KOH‐based solutions provide reaction‐rate limited etching of AlN at rates strongly dependent on the crystalline quality. The activation energy for etching is 15.5 kcal mol−1 for both polycrystalline and single‐crystal AlN, but the absolute rates are up to a factor of 103 higher for the polycrystalline material. The etching is selective over GaN and substrate materials such as Al2O3. KOH‐based solutions also attack the interfacial region between InN and GaAs causing liftoff of the epitaxial InN layers. We have also studied the wet etching characteristics of GaN, AlN, and InN in all of the common acid solutions employed for conventional semiconductors. The temperature of these solutions was varied from 23 to 85 °C, but no measurable etching was observed under any of these conditions.

Patterning of AlN, InN, and GaN in KOH‐based solutions

AlN films grown by gas-source molecular beam epitaxy were doped with different levels of Mn during growth. High resolution x-ray diffraction characterization revealed good crystallinity in single phase material, with lattice constant decreasing with increasing Mn concentration. Single phase AlMnN was found to be p type while AlMnN/AlMn mixed phase material was found to be highly conductive n type. Magnetization measurements performed with a superconducting quantum interference device magnetometer indicated ferromagnetism in single phase material persisting to 300 K and showed no evidence of room temperature magnetization in multiphase material. In particular, it was shown that Mn4N second phases are not contributing to the magnetization in the AlMnN under optimized growth conditions.

Indication of hysteresis in AlMnN

The robust radiation resistance of wide-band gap materials is advantageous for space applications, where the high-energy particle irradiation deteriorates the performance of electronic devices. We report on the effects of proton irradiation of β-Ga2O3 nanobelts, whose energy band gap is ∼4.85 eV at room temperature. Back-gated field-effect transistor (FET) based on exfoliated quasi-two-dimensional β-Ga2O3 nanobelts were exposed to a 10 MeV proton beam. The proton-dose- and time-dependent characteristics of the radiation-damaged FETs were systematically analyzed. A 73% decrease in the field-effect mobility and a positive shift of the threshold voltage were observed after proton irradiation at a fluence of 2 × 1015 cm–2. Greater radiation-induced degradation occurs in the conductive channel of the β-Ga2O3 nanobelt than at the contact between the metal and β-Ga2O3. The on/off ratio of the exfoliated β-Ga2O3 FETs was maintained even after proton doses up to 2 × 1015 cm–2. The radiation-induced damage in the β...

Influence of High-Energy Proton Irradiation on β-Ga2O3 Nanobelt Field-Effect Transistors

1. UV LEDs-Michael Shur (RPI, email shurm@rpi.edu) 2. Non-Polar GaN Growth-Jung Han (Yale, email jung.han@yale.edu) 3. High Quality AlGaN Alloys-Hongxing Jiang and Jingyu Lin (Texas Tech, email hx.jiang@ttu.edu and jingyu.lin@ttu.edu) 4. Bulk AlN for UV LEDs -L.J. Schowalter (Crystal IS, email Leo@crystal-IS.com) 5. Enhancement of the Light-Extraction Efficiency of GaN-Based Light Emitting Diodes-Jihyun Kim (Korea University, Seoul 136-701, Korea, email: hyunhyun7@.korea.ac.kr ) 6. GaN-Based Sensors-F. Ren (Univ. Florida, email ren@che.ufl.edu) 7. III-N Alloys for Solar Power Conversion-Wladek Walukievicz (LBL, email W_Walukiewicz@lbl.gov) 8. GaN HEMT Technology-Wayne Johnson (Kopin, email Wayne_Johnson@kopin.com) 9. GaN Power Devices-John Shen (Univ.Central Florida, email johnshen@mail.ucf.edu)- 10. Nitride Nanostructures-Li-Chyong Chen (National Taiwan University, email chenlc@ntu.edu.tw) 11. Radiation-Induced Defects in GaN-Alexander Polyakov (IRM, Russia, email aypolyakov@gmail.com) 12. Electron Injection Effects in GaN-L. Chernyak (Univ. Central Florida, email chernyak@physics.ucf.edu) 13. Progress and Prospect of Rare-Earth Nitrides- R. Palai ( Department of Physics, University of Puerto Rico, San Juan, PR, 00931, USA, email: r.palai@uprrp.edu)- 14. Advances in PLD of ZnO and related compounds-Ashutosh Tiwari, (Dept. of Materials Science & Engineering, University of Utah, E-mail: tiwari@eng.utah.edu) 15. ZnO nanowires and p-type doping-Deli Wang (UCSD, Electrical and Computer Engineering, email dwang@ece.ucsd.edu) 16. Multifunctional ZnO Structures-Yicheng Lu (Rutgers, email ylu@ece.rutgers.edu)- 17. ZnO/MgZnO Quantum Wells-C. Jagadish (ANU, Australia, email cxj109@rsphysse.anu.edu.au) 18. GZO TFTs-E.Fortunato(CENIMAT, FCT-UNL, Campus de Caparica, 2829-516 Caparica, Portugal, email elvira-fortunato@fct.unl.pt )

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GaN and ZnO-based materials and devices

Scandium oxide was deposited epitaxially on (0001) GaN via gas-source molecular beam epitaxy (GSMBE) using elemental Sc and an electron cyclotron resonance (ECR) oxygen plasma. HXRD indicated that the Sc 2 O 3 has a lower defect density than similarly prepared films of Gd 2 O 3 . The scandium oxide was atomically smooth, with a rms roughness of 0.5-0.8 nm, and was uniform in stoichiometry as measured by Auger electron spectroscopy (AES) depth profiling. An interface state density of mid 10 11 eV -1 cm -2 was determined from capacitance-voltage profiling using the Terman method. This interface state density was roughly a factor of five lower than that obtained from similar diodes made from SiO 2 on GaN.

Stephen J. Pearton

Papers

Patterning of AlN, InN, and GaN in KOH‐based solutions

Indication of hysteresis in AlMnN

Influence of High-Energy Proton Irradiation on β-Ga2O3 Nanobelt Field-Effect Transistors

GaN and ZnO-based materials and devices

Gadolinium Oxide and Scandium Oxide: Gate Dielectrics for GaN MOSFETs