In the last 30 days

• Open/close ZnO nanorods: synthesis, characterization and applications

  Gyu-Chul Yi et al 2005 Semicond. Sci. Technol. 20 S22 Tag this article

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  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.

• Open/close Thin film encapsulation for flexible AM-OLED: a review

  Jin-Seong Park et al 2011 Semicond. Sci. Technol. 26 034001 Tag this article

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  Flexible organic light emitting diode (OLED) will be the ultimate display technology to customers and industries in the near future but the challenges are still being unveiled one by one. Thin-film encapsulation (TFE) technology is the most demanding requirement to prevent water and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This work provides a review of promising thin-film barrier technologies as well as the basic gas diffusion background. Topics include the significance of the device structure, permeation rate measurement, proposed permeation mechanism, and thin-film deposition technologies (Vitex system and atomic layer deposition (ALD)/molecular layer deposition (MLD)) for effective barrier films.

• Open/close Digital-circuit analysis of short-gate tunnel FETs for low-voltage applications

  Jing Zhuge et al 2011 Semicond. Sci. Technol. 26 085001 Tag this article

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  This paper investigates the potential of tunnel field-effect transistors (TFETs), with emphasis on short-gate TFETs, by simulation for low-power digital applications having a supply voltage lower than 0.5 V. A transient study shows that the tunneling current has a negligible contribution in charging and discharging the gate capacitance of TFETs. In spite of a higher resistance region in the short-gate TFET, the gate (dis)charging speed still meets low-voltage application requirements. A circuit analysis is performed on short-gate TFETs with different materials, such as Si, Ge and heterostructures in terms of voltage overshoot, delay, static power, energy consumption and energy delay product (EDP). These results are compared to MOSFET and full-gate TFET performance. It is concluded that short-gate heterostructure TFETs (Ge–source for nTFET, In _0.6Ga _0.4As–source for pTFET) are promising candidates to extend the supply voltage to lower than 0.5 V because they combine the advantage of a low Miller capacitance, due to the short-gate structures, and strong drive current in TFETs, due to the narrow bandgap material in the source. At a supply voltage of 0.4 V and for an EOT and channel length of 0.6 nm and 40 nm, respectively, a three-stage inverter chain based on short-gate heterostructure TFETs saves 40% energy consumption per cycle at the same delay and shows 60%–75% improvement of EDP at the same static power, compared to its full-gate counterpart. When compared to the MOSFET, better EDP can be achieved in the heterostructure TFET especially at low static power consumption.

• Open/close 1024 × 1024 pixel mid-wavelength and long-wavelength infrared QWIP focal plane arrays for imaging applications

  S D Gunapala et al 2005 Semicond. Sci. Technol. 20 473 Tag this article

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  Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 × 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEΔ T) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEΔ T of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In this paper, we will discuss the performance in terms of quantum efficiency, NEΔ T, uniformity, operability and modulation transfer functions.

• Open/close Transparent conducting oxide semiconductors for transparent electrodes

  Tadatsugu Minami 2005 Semicond. Sci. Technol. 20 S35 Tag this article

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  The present status and prospects for further development of polycrystalline or amorphous transparent conducting oxide (TCO) semiconductors used for practical thin-film transparent electrode applications are presented in this paper. The important TCO semiconductors are impurity-doped ZnO, In ₂O ₃ and SnO ₂ as well as multicomponent oxides consisting of combinations of ZnO, In ₂O ₃ and SnO ₂, including some ternary compounds existing in their systems. Development of these and other TCO semiconductors is important because the expanding need for transparent electrodes for optoelectronic device applications is jeopardizing the availability of indium-tin-oxide (ITO), whose main constituent, indium, is a very expensive and scarce material. Al- and Ga-doped ZnO (AZO and GZO) semiconductors are promising as alternatives to ITO for thin-film transparent electrode applications. In particular, AZO thin films, with a low resistivity of the order of 10 ⁻⁵ Ω cm and source materials that are inexpensive and non-toxic, are the best candidates. However, further development of the deposition techniques, such as magnetron sputtering or vacuum arc plasma evaporation, as well as of the targets is required to enable the preparation of AZO and GZO films on large area substrates with a high deposition rate.

• Open/close The status and perspectives of metal oxide thin-film transistors for active matrix flexible displays

  Jae Kyeong Jeong 2011 Semicond. Sci. Technol. 26 034008 Tag this article

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  The purpose of this paper is to give an overview of the state-of-the-art of metal oxide thin-film transistors (TFTs). First, the question of how to achieve high-performance oxide TFTs is addressed, including the exploration of new channel materials, the realization of low-resistance ohmic contacts and the implementation of high- k dielectric materials as the gate insulator. The electrical instability of the oxide TFTs is also discussed, which is critical for their application in flexible backplane electronics: special attention is given to the understanding of the degradation mechanism of oxide TFTs against bias thermal stress (BTS) and light illuminated BTS. Finally, the recent application of oxide TFTs in active matrix displays, such as electronic paper, liquid crystal displays and organic light-emitting diodes, is addressed.

• Open/close Large-area OLED lightings and their applications

  J W Park et al 2011 Semicond. Sci. Technol. 26 034002 Tag this article

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  In this paper, we review the key issues related to the fabrication of large-area organic light-emitting devices (OLEDs) for lighting applications. We discuss the origin of a short-circuit problem, luminance non-uniformity, hot spot, efficiency reduction (power loss), and heat generation and present the way of suppressing them. We also introduce three different application areas of large-area OLED lighting panels. They can be integrated with a solar cell for power recycling or inorganic LEDs for emotional lightings. The feasibility of using OLEDs for the application of visible-light communications is also reviewed.

• Open/close THz imaging and sensing for security applications—explosives, weapons and drugs

  John F Federici et al 2005 Semicond. Sci. Technol. 20 S266 Tag this article

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  Over the past 5 years, there has been a significant interest in employing terahertz (THz) technology, spectroscopy and imaging for security applications. There are three prime motivations for this interest: (a) THz radiation can detect concealed weapons since many non-metallic, non-polar materials are transparent to THz radiation; (b) target compounds such as explosives and illicit drugs have characteristic THz spectra that can be used to identify these compounds and (c) THz radiation poses no health risk for scanning of people. In this paper, stand-off interferometric imaging and sensing for the detection of explosives, weapons and drugs is emphasized. Future prospects of THz technology are discussed.

• Open/close Applications of two-photon processes in semiconductor photonic devices: invited review

  Alex Hayat et al 2011 Semicond. Sci. Technol. 26 083001 Tag this article

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  Semiconductor photonics is an advanced field, both from fundamental and applicative points of view, aimed at the integration of the unique features of optical communications and quantum optics with the miniaturization and controllability of semiconductors. Many classical and quantum applications may benefit from interaction between optical signals, usually implemented by nonlinear optical processes of various orders. The efficiency of such processes in semiconductors is being constantly enhanced, assisted by the progress in ultrashort laser pulses and ultra-sensitive detectors, enabling practical devices. In this review, the lowest order of nonlinear interactions-–the two-photon processes in semiconductors—are discussed, and their applications to a variety of novel classical and quantum configurations are reviewed.

• Open/close Growth and properties of III–V compound semiconductor heterostructure nanowires

  Q Gao et al 2011 Semicond. Sci. Technol. 26 014035 Tag this article

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  We review various GaAs-based axial and radial nanowire heterostructures grown on (1 1 1)B GaAs substrates by metal organic chemical vapor deposition via vapor–liquid–solid mechanism. Transmission electron microscopy, time-resolved photoluminescence and micro-Raman spectroscopy have been used to understand the crystal structure, non-radiative surface and bulk defects, carrier lifetime and strain effects on the bandgap energy.