• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.60-66
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• 1998

The hot carrier induced performance degradation of 0.8${\mu}{\textrm}{m}$ RF NMOSFET has been investigated within the general framework of the degradation mechanism. The device degradation model of an unit finger gate MOSFET could be applied for the device degradation of the multi finger gate RF NMOSFET. The reduction of cut-off frequency and maximum frequency can be explained by the transconductance reduction and the drain output conductance increase, which are due to the interface state generation after the hot carrier stressing. From the correlation between hot carrier induced DC and RF performance degradation, we can predict the RF performance degradation just by the DC performance degradation measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.387-387
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• 2010

최근 ZnO 박막은 투명 박막, 태양전지, LED 등으로의 응용을 위한 새로운 기능성 박막으로 활발히 연구되어 지고 있다. ZnO 기반의 투명 박막 트랜지스터는 상온에서 증착 가능하여 유리기판을 이용한 광학소자와 플라스틱 기판을 이용한 플럭서블 소자 같은 차세대 전자소자를 구현 할 수 있다. 본 연구에서는 RF Magnetron Sputtering System을 이용하여 coming 1737 유리기판 위에 ZnO 박막을 공정압력에 따라 증착하고, 투명 반도체에 적합한 활용을 위한 구조적, 광학적 분석을 실시하였다. 박막 증착 조건은 초기 압력 $1.0{\times}10^{-6}$Torr, RF 파워는 100W, Ar 유량은 100sccm, 그리고 증착온도는 상온이었다. 증착 압력은 $7.0{\times}10^{-3}$, $2.0{\times}10^{-2}$, $7.0{\times}10^{-2}$Torr로 변화시켰다. 표면 분석 (SEM, AFM) 결과 증착압력이 고진공으로 변화함에 따라 결정립들이 감소하였고 RMS roughness값이 낮아졌다. 그리고 XRD 분석을 통해 피크강도는 증가하고 FWHM은 감소함을 보이고 있는데 이는 결정성이 좋아짐을 나타낸다. 그리고 광학 투과도를 통해 가시광 영역에서의 높은 투과도(85% 이상)을 확인하였고, 고진공으로 변화함에 따라 밴드갭이 넓어지는 것을 확인하였다.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.83-87
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• 2023

In the field of electronics and semiconductor technology, innovative semiconductor material research to replace Si is actively ongoing. However, while research on alternative materials is underway, there is a significant lack of studies regarding the relationship between 2D materials used as channels in transistors, especially parasitic resistance, and RF (radio frequency) applications. This study systematically analyzes the impact on electrical performance with a focus on various transistor structures to address this gap. The research results confirm that access resistance and contact resistance act as major factors contributing to the degradation of semiconductor device performance, particularly when highly scaled down. As the demand for high-frequency RF components continues to grow, establishing guidelines for optimizing component structures and elements to achieve desired RF performance is crucial. This study aims to contribute to this goal by providing structural guidelines that can aid in the design and development of next-generation RF transistors using 2D materials as channels.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.302-311
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• 2014

In this work, a FTTL (fishbone-type transmission line) structure was fabricated on PES (polyether sulfone) for a realization of transparent flexible wireless communication device, and its RF characteristics were investigated. According to the results, the FTTL on PES showed a short wavelength characteristic compared with conventional coplanar waveguide. Concretely, the wavelength of the FTTL was 2.23 mm at 50 GHz, which was 56.6 % of the conventional coplanar waveguide. According to the bandwidth extraction result, the passband of the FTTL on PES was 608 GHz. Unlike conventional periodic structures, the characteristic impedance of the FTTL on PES showed a very low frequency dependency, which means that the FTTL on PES can be used for application to transmission line and distributed passive components with a broadband operation frequency.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.70-77
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• 2014

In this work, we studied basic characteristics of transmission lines employing various PSS (periodic strip structure) on silicon substrate for application to a miniaturization of RF components. According to the results, the transmission lines employing various PSS showed wavelength shorter than conventional coplanar waveguide due to their strong wave characteristics. Especially, with-contact structure was most effective for a miniaturization of RF component. Concretely, the size of the transmission line employing with-contact was only 4.39 % of the conventional coplanar waveguide, According to the bandwidth extraction result, the bandwidth of the transmission lines employing various PSS structures were wider than 384 GHz. Above results indicate that the transmission lines employing various PSS can be effectively used for application to a broadband and miniature RF component, and especially, with-contact is most effective for a miniaturization of RF components.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3435-3440
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• 2010

Unlike the electric method capable of checking only product defect, the real time optical metrology is suggested for measuring and visualizing vibration with respect to position of surface acoustic wave in RF device. The measuring limits and conditions for surface acoustic wave is given, and the interference and diffraction due to RF signal are analyzed by optical interpretation. A single mode laser and a 105MHz-center-frequency repeater filter were employed for experiments and theoretical analysis. In this paper, the optical metrology providing visual energy distribution and real time inspection for surface acoustic wave is proposed for development of high quality multi-service and multi-frequency RF module.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.2 s.332
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• pp.9-14
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• 2005

This paper reports the hot carrier induced RF performance degradation of bulk dynamic threshold voltage MOSFET (B-DTMOS) compared with bulk MOSFET (B-MOS). In the normal and moderate mode operations, the degradations of cut-off frequency $(f_{T})$ and minimum noise figure $(F_{min})$ of B-DTMOS are less significant than those of B-MOS devices. Our experimental results show that the RF performance degradation is more significant than the U performance degradation after hot carrier stressing. Also, the degradation characteristics of RF power Performance of B-DTMOS due to hot carrier effects are measured for the first time.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.364-364
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• 2012

평판 디스플레이 분야에 투명 비정질 산화물 반도체는 박막 트렌지스터(Thin film transistor; TFT)소자의 채널층으로 사용할 수 있다. 투명 비정질 산화물 반도체 IGZO (In-Ga-Zn-O)는 다른 비정질 재료에 비해 높은 전하 이동도를 가지기 때문에 우수한 성능의 TFT소자를 제작할 수 있다. 본 연구에서는 RF magnetron sputtering법으로 corning 1737 유리기판 위에 RF 파워의 변화에 따라 증착한 IGZO박막의 광학적 전기적 특성 변화를 연구하였다. 박막 증착 조건은 초기 압력 $2.0{\times}10^{-6}Torr$, 증착 압력 $2.0{\times}10^{-2}Torr$, 반응가스 Ar 25 sccm, 증착 온도는 실온으로 고정하였으며, 공정변수로 RF 파워를 25 w, 50 w, 75 w, 100 w로 변화시키며, IGZO 타겟은 $In_2O_3$, $Ga_2O_3$, ZnO 분말을 각각 1 : 1 : 2mol% 조성비로 혼합하여 소결한 타겟을 사용하였다. 표면분석(AFM)결과 RF 파워가 증가함에 따라 거칠기가 증가하였으며, XRD 분석결과 Bragg's 법칙을 만족하는 피크가 나타나지 않는 비정질 구조임을 확인할 수 있었다. 가시광 영역에서 (450~700 nm) 25 w일 때 85% 이상을 확인하였고, RF 파워가 증가할수록 밴드갭이 감소하는 것을 확인하였다. RF 파워가 100 w인 경우 carrier 밀도는 $7.7{\times}10^{19}cm^{-3}$, Mobility $8.42cm^2V-s$, Resistivity $9.45{\times}10^{-3}{\Omega}-cm$로 투명 전도막의 특성을 보였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.7
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• pp.1321-1325
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• 2001

In this article, piezoelectric films and their application for film bulk acoustic resonator (FBAR) devices are presented. The FBAR is composed of piezoelectric film sandwiched between top and bottom electrodes and an acoustic reflector of SiO2/W stacked multilayers. Various FBAR devices were fabricated and evaluated through simulation and measurement. The insertion loss, return loss and Q-factor were observed to be reasonably high and good. The FBAR technology seems very promising particularly for RF band filter application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1239-1247
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• 2012

In this paper, design and fabrication of solid state power amplifier(SSPA) using GaN HEMT chip for X-band frequency are presented. The SSPA consists of the power supply for stable power and the control unit for communication and controlling the internal module, the RF Part to amplify RF signal, In particular the adopted active device for the RF Parts is GaN HEMT Bare chip of TriQuint company, the RF parts consists of pre-stage, drive-stage, main power-stage and each amplifier is designed with input and out matching circuit. The developed power amplifier demonstrated more than 300 W peak output power in condition of 26 % duty, max. pulse width 100us for the X-band frequency( 500 MHz bandwidth) and can apply to marine radar systems.