• Journal of Information Display
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• 제10권4호
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• pp.143-148
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• 2009

The theoretical current density equations for organic semiconductors was derived according to the internal carrier emission equation based on the diffusion model at the Schottky barrier contact and the mobility equation based on the field dependence model, the so-called "Poole-Frenkel mobility model." The electric field becomes constant because of the absence of a space charge effect in the case of a higher injection barrier height and a lower sample thickness, but there is distribution in the electric field because of the space charge effect in the case of a lower injection barrier height and a higher sample thickness. The transition between the injection- and bulk-limited currents was presented according to the Schottky barrier height and the sample thickness change.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.268-270
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• 2002

반도체소자의 전자전송특성을 해석하기 위하여 임팩트이온화현상은 매우 중요하다. 임팩트이온화는 전자-정공쌍들의 생성과정이므로 소자에 인가되는 전압이나 온도에 따라 소자의 특성이 변화될 수 있다. 본 연구에서는 Constant Voltage 스켈링이론을 적용하여 게이트 길이를 50nm까지 스케일 다운하였으며 TCAD시뮬레이터를 이용하여 세 가지 모델-Van Overstraeten, Okuto, Ours-에 대하여 임팩트이온화와 breakdown등을 비교 분석하였다.

• 전자공학회논문지
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• 제54권3호
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• pp.31-36
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• 2017

본 논문에서는 가상의 적외선 영상을 투사하여 적외선 검출기의 성능 평가를 위한 목적으로 사용되는 적외선 영상 투사장치 (Infrared scene projector, IRSP)의 내부에서 적외선을 방사하는 역할을 하는 적외선 에미터 소자에 대한 연구가 수행되었다. 적외선 에미터 소자의 구조를 설계한 후 설계된 소자의 특성 파라미터들을 추출하였으며 각 특성 파라미터에 근거한 소자의 성능을 유한 요소법을 통해 예측하였다. 또한 소자를 구성하는 각 부분의 특성에 따른 물질 선정 후 MEMS 기반 반도체 공정기술을 적용하여 에미터 단위소자를 제작하였고 중적외선 대역($3{\sim}5{\mu}m$)의 적외선을 관찰할 수 있는 적외선 영상 현미경을 사용하여 진공 환경을 갖춘 챔버 내부에서 소자의 성능을 측정한 결과 최대 423K의 유효온도 및 22msec의 응답 시간을 나타내는 것을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권1호
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• pp.51-55
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• 2007

This paper investigates the subthreshold behavior of Fin Field Effect Transistor (FinFET). The FinFET is considered to be an alternate MOSFET structure for the deep sub-micron regime, having excellent device characteristics. As the channel length decreases, the study of subthreshold behavior of the device becomes critically important for successful design and implementation of digital circuits. An accurate analysis of subthreshold behavior of FinFET was done by simulating the device in a 3D process and device simulator, Taurus. The subthreshold behavior of FinFET, was measured using a parameter called S-factor which was obtained from the $In(I_{DS})\;-\;V_{GS}$ characteristics. The value of S-factor of devices of various fin dimensions with channel length $L_g$ in the range of 20 nm - 50 nm and with the fin width $T_{fin}$ in the range of 10 nm - 40 nm was calculated. It was observed that for devices with longer channel lengths, the value of S-factor was close to the ideal value of 60 m V/dec. The S-factor increases exponentially for channel lengths, $L_g\;<\;1.5\;T_{fin}$. Further, for a constant $L_g$, the S factor was observed to increase with $T_{fin}$. An empirical relationship between S, $L_g$ and $T_{fin}$ was developed based on the simulation results, which could be used as a rule of thumb for determining the S-factor of devices.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권1호
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• pp.7-15
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• 2015

We have investigated electrical properties of graphene/Ge Schottky barrier diode (SBD) fabricated on Ge film epitaxially grown on Si substrate. When decreasing temperature, barrier height decreased and ideality factor increased, implying their strong temperature dependency. From the conventional Richardson plot, Richardson constant was much less than the theoretical value for n-type Ge. Assuming Gaussian distribution of Schottky barrier height with mean Schottky barrier height and standard deviation, Richardson constant extracted from the modified Richardson plot was comparable to the theoretical value for n-type Ge. Thus, the abnormal temperature dependent Schottky behavior of graphene/Ge SBD could be associated with a considerable deviation from the ideal thermionic emission caused by Schottky barrier inhomogeneities.

• ETRI Journal
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• 제19권4호
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• pp.344-362
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• 1997

The delay which is one of the quality of service parameters is considered to be a crucial factor for the effective usage of real-time audio and video streams in interactive multimedia collaborations. Among the various causes of the delay, we focus in this paper on the local delay concerned with the schemes which handle continuous inflow of encoded data from constant or variable bit-rate audio and video encoders. We introduce two kinds of implementation approaches, pull model and push model. While the pull model periodically pumps out the incoming data from the system buffer, the push model receives events from the device drivers. From our experiments based on Windows NT 3.51, it is shown that the push model outperforms the other for both constant and variable bit-rate streams in terms of the local delay, when the system suffers reasonable loads. We interpret this experimental data with M/G/1 multiple vacation queuing theories, and show that it is consistent with the queuing theoretic interpretations.

• Journal of the Optical Society of Korea
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• 제19권2호
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• pp.149-153
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• 2015

A digital micro-mirror device (DMD) has the potential to modulate an incident wave with high speed, and the application for holographic display has been studied by many researchers. However, the quality of reconstructed image isn't good in comparison with that from a gray-scale amplitude-only hologram since it is a binary amplitude-only spatial light modulator (SLM). In this paper, we suggest a method generating a set of binary holograms to improve the quality of the reconstructed image. Here, we are concerned with the case for which the object plane is positioned at the Fourier domain of the plane of the SLM. In this case, any point in the Fourier plane is related to all points in the hologram. So there is a chance to generate a set of binary holograms illuminated by incident wave with constant optical power. Moreover, we find an interesting fact that the quality of reconstructed image is improved when the spatial frequency bandwidth of the binary hologram is limited. Therefore, we propose an iterative segmentation algorithm generating a set of binary holograms that are designed to be illuminated by the wave with constant optical power. The feasibility of our method is experimentally confirmed with a DMD.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.107-112
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• 2005

We present an AlGaN/GaN metal-insulator-semiconductor-heterostructure field effect transistor (MIS-HFET) with an $Al_2O_3-HfO_2$ laminated high-k dielectric, deposited by plasma enhanced atomic layer deposition (PEALD). Based on capacitance-voltage measurements, the dielectric constant of the deposited $Al_2O_3-HfO_2$ laminated layer was estimated to be as high as 15. The fabricated MIS-HFET with a gate length of 102 m exhibited a maximum drain current of 500 mA/mm and maximum tr-ansconductance of 125 mS/mm. The gate leakage current was at least 4 orders of magnitude lower than that of the reference HFET. The pulsed current-voltage curve revealed that the $Al_2O_3-HfO_2$ laminated dielectric effectively passivated the surface of the device.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.19-26
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• 2013

본 논문에서는 시분산 채널에서 발생되는 진폭과 위상 찌그러짐을 동시에 보상할 수 있는 적응 등화 알고리즘인 MMA (Multiple Modulus Algorithm)와 S-MMA (Sliced-MMA)의 성능을 비교하였다. 기존 CMA 알고리즘은 진폭만을 복원하며 위상의 복원이 불가능하므로 이를 위해 별도의 부가 회로가 필요케 되는 단점을 극복하기 위해 MMA 알고리즘에서는 개선된 비용 함수를 적용하였다. MMA 알고리즘에서는 탭 계수의 갱신을 위해 dispersion constant를 이용한 오차를 표현하고, S-MMA에서는 결정 장치의 출력 (Sliced-Symbol)을 고려한 dispersion constant를 이용한 오차를 표현하게 되어, 이와 같은 오차 신호의 차이로 인하여 적응 등화 알고리즘은 서로 상이한 성능을 갖게 된다. 논문에서 QAM 신호의 차수를 16과 64로 한 후 동일 채널을 통과하여 신호를 수신할 때 이들 적응 등화 알고리즘의 성능을 나타내는 지수로 복원 성상도, 잔류 isi, MD 및 SER을 적용하여 비교한다. 시뮬레이션 결과 S-MMA가 QAM의 차수가 높을수록 MMA보다 SER 성능이 개선으로 Roburstness가 개선됨을 확인하였다.

• 한국정보과학회논문지:정보통신
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• 제37권6호
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• pp.444-452
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• 2010

IPTV의 채널을 변경할 경우 채널 변경 시 소요되는 시간을 피하기 위해, 시스템은 사용자가 원하는 채널을 사전 미리 예측해 해당 데이터를 수신하고 있어야 한다. 사용자가 이용할 채널들에 대해 예측하는 정확도는 전체 IPTV 시스템의 성능을 결정짓는 가장 중요한 요소로, 기존의 연구들은 여러 데이터를 활용하여 사용자가 변경할 채널들에 대해 예측하는 방법을 제시했다. 이런 예측에 근거한 방법들은 사용자의 채널이동 성향이나 다양한 채널 변경 패턴에 따라 일정한 성능을 보장하지 못한다. 본 논문에서는 리모컨의 채널 번호 정보를 활용하여 채널 변경 시 지연을 줄이거나 회피하기 위해 일정한 성능을 보장하는 방법을 제시한다.