• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.763-766
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• 2010

By improving the conducting process of metal source/drain (S/D) in direct contact with the channel, schottky barrier metal-oxide-semiconductor field effect transistors (SB MOSFETs) reveal low extrinsic parasitic resistances, offer easy processing and allow for well-defined device geometries down to the smallest dimensions. In this work, we investigated the arrhenius plots of the SB MOSFETs with different S/D schottky barrier (SB) heights between simulated and experimental current-voltage characteristics. We fabricated SB MOSFETs using difference S/D metals such as Cr (${\Phi}_{Cr}$ ~4.5 eV) and Ni (${\Phi}_{Ni}$~5.2 eV), respectively. Schottky barrier height (${\Phi}_B$) of the fabricated devices were measured to be 0.25~0.31 eV (Cr-S/D device) and 0.16~0.18 eV (Ni-S/D device), respectively in the temperature range of 300 K and 475 K. The experimental results have been compared with 2-dimensional simulations, which allowed bandgap diagram analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.91-107
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• 2014

Device-to-device (D2D) communication is an excellent technology to improve the system capacity by sharing the spectrum resources of cellular networks. Multicast service is considered as an effective transmission mode for the future mobile social contact services. Therefore, multicast based on D2D technology can exactly improve the spectrum resource efficiency. How to apply D2D technology to support multicast service is a new issue. In this paper, a resource allocation scheme based on cognitive radio (CR) for D2D underlay multicast communication (CR-DUM) is proposed to improve system performance. In the cognitive cellular system, the D2D users as secondary users employing multicast service form a group and reuse the cellular resources to accomplish a multicast transmission. The proposed scheme includes two steps. First, a channel allocation rule aiming to reduce the interference from cellular networks to receivers in D2D multicast group is proposed. Next, to maximize the total system throughput under the condition of interference and noise impairment, we formulate an optimal transmission power allocation jointly for the cellular and D2D multicast communications. Based on the channel allocation, optimal power solution is in a closed form and achieved by searching from a finite set and the interference between cellular and D2D multicast communication is coordinated. The simulation results show that the proposed method can not only ensure the quality of services (QoS), but also improve the system throughput.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.61-66
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• 1997

In this paper we report the fabrication of an InGaAs metal-semiconductor-metal (MSM) photodiode(PD) which an InAlAs barrier enhancement layer that has very low dark current and high speed chracteristics. The detector using Cr/Au schottky metal fingers with 4um spacing on a large active area of 300*300um$^{2}$ offers a low dark current of 38nA at 10V, a low capacitance of 0.8pF, and a high 3-dB bandwidth of 2.4 GHz. To our knowledge, these characteristics are better than any previously published results obtained from large area InGaAs MSM PD's. The RC equivalent model and frequency domain current response model considering transit time were also used to analyze the frequency characteristic of the fabricated device.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1088-1092
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• 1995

In this paper, we evaluated the sputter-deposited Cr/Cu thin film fuses on $Al_2O_3$ substrates by the adhesive, breaking and repetitive over-current test as a function of temperature on them. Each Cr and Cu was deposited $1700{\pm}300{\AA},\;3700{\pm}300{\AA}$ using RF sputtering unit. The electroplated Cu of $25{\mu}m$ thickness was added in order to make sensitive thin film fuse of the normal current 15[A]. The adhesive strength and the number of repetition were Increasing and then decreasing with the temperature. The maximum adhesive strength of over $9kgf/9mm^2$ was obtained at $400^{\circ}C$. In the breaking test, the post-arc time characteristic was better than any other factor.

• Proceedings of the Korean Magnestics Society Conference
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• 2010.06a
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• pp.79-79
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• 2010

Semimetallic bismuth (Bi) has been extensively investigated over the last decade since it exhibits very intriguing transport properties due to their highly anisotropic Fermi surface, low carrier concentration, long carrier mean free path l, and small effective carrier mass $m^*$. In particular, the great interest in Bi nanowires lies in the development of nanowire fabrication methods and the opportunity for exploring novel low-dimensional phenomena as well as practical application such as thermoelectricity[1]. In this work, we introduce a self-assembled interconnection of nanostructures produced by an on-film formation of nanowires (OFF-ON) method in order to form a highly ohmic Bi nanobridge. A Bi thin film was first deposited on a thermally oxidized Si (100) substrate at a rate of $40\;{\AA}/s$ by radio frequency (RF) sputtering at 300 K. The sputter system was kept in an ultra high vacuum (UHV) of $10^{-6}$ Torr before deposition, and sputtering was performed under an Ar gas pressure of 2m Torr for 180s. For the lateral growth of Bi nanowires, we sputtered a thin Cr (or $SiO_2$) layer on top of the Bi film. The Bi thin films were subsequently put into a custom-made vacuum furnace for thermal annealing to grow Bi nanowires by the OFF-ON method. After thermal annealing, the Bi nanowires cannot be pushed out from the topside of the Bi films due to the Cr (or $SiO_2$) layer. Instead, Bi nanowires grow laterally as a mean s of releasing the compressive stress. We fabricated a self-assembled Bi nanobridge (d=192 nm) device in-situ using OFF-ON through annealing at $250^{\circ}C$ for 10hours. From I-V measurements taken on the Bi nanobridge device, contacts to the nanobridge were found highly ohmic. The quality of the Bi nanobridge was also proved by the high MR of 123% obtained from transverse MR measurements. These results manifest the possibility of self-assembled nanowire interconnection between various nanostructures for a variety of applications and provide a simple device fabrication method to investigate transport properties on nanowires without complex patterning and etching processes.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.27-31
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• 2008

Due to the increasing need for miniaturization of electronic device, embedded resistor technology using thick film resistance paste to embed resistors currently mounted on the board thus effectively reducing board size, is being extensively researched. In this research, thick film resistor paste having $0.35{\sim}4k{\Omega}/sq$ range of resistivity were fabricated using mixtures of carbon black and epoxy resin. In order to adjust the TCR (temperature coefficient resistivity), TCR modifiers such as Ni-Cr alloy, $SiO_2$ powder were added and were able to improve on TCR value with $100ppm/^{\circ}C$. Finally embedded resistor board using thick film resistance paste were fabricated. Stable resistivity value and reliability results were achieved.