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

Several hundred thousands of tons of ZnO are used by per year, e.g. as an additive to concrete or to rubber. In the field of optoelectronics, ZnO holds promises as a material for a blue/UV optoelectronics, alternatively to GaN, as a cheap, transparent, conducting oxide, as a material for electronic circuits, which are transparent in the visible or for semiconductor spintronics. The main problem is presently, however, a high, reproducible and stable p-doping. We review in this contribution partly critically the material growth, fundamental properties of ZnO and of ZnO-based nanostructures, doping as well as present and future applications, with emphasis on the electronic and optical properties including stimulated emission. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

ZnO : From basics towards applications

ZnO is presently experiencing a research boom with more than 2000 ZnO-related publications in 2005. This phenomenon is triggered, for example, by hope to use ZnO as a material for blue/UV optoelectronics as an alternative to GaN, as a cheap, transparent, conducting oxide, as a material for electronic circuits that are transparent in the visible or for semiconductor spintronics. Currently, however, the main problem is to achieve high, reproducible and stable p-doping. Herein, we critically review aspects of the material growth, fundamental properties of ZnO and ZnO-based nanostructures and doping as well as present and future applications with emphasis on the electronic and optical properties including stimulated emission.

ZnO: Material, Physics and Applications

This paper presents a review of current research activities on ZnO nanorods (or nanowires). We begin this paper with a variety of physical and chemical methods that have been used to synthesize ZnO nanorods (or nanowires). There follows a discussion of techniques for fabricating aligned arrays, heterostructures and doping of ZnO nanorods. At the end of this paper, we discuss a wide range of interesting properties such as luminescence, field emission, gas sensing and electron transport, associated with ZnO nanorods, as well as various intriguing applications. We conclude with personal remarks on the outlook for research on ZnO nanorods.

http://iopscience.iop.org/article/10.1088/0268-1242/20/4/003/pdf

ZnO nanorods: synthesis, characterization and applications

Digital information processing in molecular systems.

We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal ZnO nanorods were prepared using catalyst-free metalorganic vapor phase epitaxy. Although typical ZnO nanorod FETs exhibited good electrical characteristics, with a transconductance of ∼140nS and a mobility of 75cm2∕Vs, the device characteristics were significantly improved by coating a polyimide thin layer on the nanorod surface, exhibiting a large turn-ON/OFF ratio of 104–105, a high transconductance of 1.9μS, and high electron mobility above 1000cm2∕Vs. The role of the polymer coating in the enhancement of the devices is also discussed.

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Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors

Logic devices, including OR, AND, NOT, and NOR gates, based on single-crystalline ZnO nanorods are demonstrated. In these devices, ZnO nanorods are employed as semiconducting channels. They control metal/oxide semiconductor junction characteristics, to yield either good ohmic or Schottky contacts, ensuring fabrication of high-performance Schottky diodes and metal-semiconductor field-effect transistors.

ZnO Nanorod Logic Circuits

The authors thank Prof. Hee Cheul Choi at POSTECH for helpful discussion. This work was supported by the Korea Research Foundation Grant (KRF-2003-041-C00132).

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ZnO Nanorod Biosensor for Highly Sensitive Detection of Specific Protein Binding

A variety of elements and crystal structures of metal oxides allows for the integration of many magnetic, electronic, and optoelectronic functions into the materials, providing significant potential for realizing a diverse range of active devices [1]. For example, transparent conducting oxides (TCOs) such as indium-tin-oxide (ITO), SnO2, and ZnO have widely been used as window electrodes for flat panel displays, touch panels, and solar cells because of their unique features of excellent optical transparency and controllable electrical conductivity by impurity doping. Conventional TCOs have also been studied as semiconducting channel of thin-film transistors (TFTs) for invisible electronic circuit applications, but which are limited by the poor device performance resulting from the lack of high quality oxide semiconductor materials. The key parameters of SnO2 and ZnO TFTs, field-effect mobilities have been ranged from 0.1 to 10 cm2/Vs [2]. Since charge scattering by ionized impurities and grain-boundaries is thought to limit the performance, preparation of high-quality single-crystalline TCO with a low background carrier concentration is challengeable.

Jin Suk Kim

Papers

Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors

ZnO Nanorod Logic Circuits

ZnO Nanorod Biosensor for Highly Sensitive Detection of Specific Protein Binding

High performance logic devices based on single crystalline ZnO nanorods