• 진공이야기
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• 제2권2호
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• pp.24-28
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• 2015

The brightness of an electron source, along with the aberrations of an objective lens, determines the image resolution and beam current on samples, which are two important parameters for evaluating the performance of an electron microscope. Here we introduce thermal electron source, Schottky emitter and cold field electron emitter. Thermal electron source is the cheapest and stable electron source but it has the lowest brightness. Schottky emitter is 10000 times brighter than tungsten thermal electron source, but requires ultrahigh vacuum operating condition. Cold field electron emitter is 10 times brighter than Schottky emitters, but it is rather unstable and its operation requires most stringent vacuum condition, hindering its widespread use.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.105.1-105.1
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• 2013

Schottky Emitter (SE)는 미국 FEI의 L. W. Swanson 그룹이 개발하여 상용화시킨 전자원이며, 고분해능 전자현미경용 전자원 시장에서 가장 큰 점유율을 차지하고 있다. 상온에서 작동하는 cold field emitter (CFE)에 비해 휘도(brightness)가 10~100배 정도 낮으나, 10-10 Torr 영역의 초고진공에서도 수시간 미만의 방출전류 안정성을 가진 CFE에 비해 수개월이상 안정된 방출전류를 전자현미경에 제공하므로, 반도체 측정, 검사 등과 같이 고분해능과 안정성이 동시에 요구되는 분야에서는 SE전자원은 필수 요소가 되어있다. 현재 SE 전자원은 일본, 미국, 영국의 4개사가 과점하고 있는 상태이다. SE 전자원이 안정되게 작동하기 위해서는 10~10 Torr 영역의 초고진공 환경이 요구된다. 한국 전자현미경 업체는 국책과제 등을 통해 SE 전자총을 개발해 왔으나, 진공기술과 광학계 설계기술이 부족하여 안정된 SE 전자총의 개발에 성공하지 못하였다. 본 발표에서는 10~10 Torr 영역에서 200 microA 이상의 전류를 안정되게 방출하는 SE 전자총의 전자빔 방출 및 진공특성을 보고한다. 시뮬레이션을 통해 구한 전차총의 전자원 위치 변화, 건렌즈 초점거리, 수차 등의 광학특성을 보여준다. 전자총을 전자현미경 경통에 탑재하고 제어하기 위해서는 전자총뿐만 아니라 전자현미경 전체의 광학특성을 이해할 필요가 있다. 전자총을 현미경에 통합 제어하기 위한 기술과제에 대해서도 간략히 보고한다.

• 한국전기전자재료학회논문지
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• 제15권5호
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• pp.449-454
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• 2002

The use of a thin film of indium between the ITO and the $n^+-lnP$ contact layers for InP/InGaAs HPTs was studied without degrading its excellent optical transmittance properties. $ITO/n^+-lnP$ ohmic contact was successfully achieved by the deposition of indium and annealing. The specific contact resistance of about $6.6{\times}10^{-4}\Omega\textrm{cm}^2$ was measured by use of the transmission line method (TLM). However, as the thermal annealing was just performed to $ITO/n^+-lnP$ contact without the deposition of indium between ITO and $n^+-lnP$, it exhibited Schottky characteristics. In the applications, the DC characteristics of InP/InGaAs HPTs with ITO emitter contacts was compared with those of InP/InGaAs HBTs with the opaque emitter contacts.

• 한국전기전자재료학회논문지
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• 제29권3호
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• pp.147-151
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• 2016

Graphene has a monolayer crystal structure formed with C-atoms and has been used as a base layer of HETs (hot electron transistors). Graphene HETs have exhibited the operation at THz frequencies and higher current on/off ratio than that of Graphene FETs. In this article, we report on the preliminary results of current characteristics from the HETs which are fabricated utilizing highly doped Si collector, graphene base, and 5 nm thin $Al_2O_3$ tunnel layers between the base and Ti emitter. We have observed E-B forward currents are inherited to tunneling through $Al_2O_3$ layers, but have not noticed the Schottky barrier blocking effect on B-C forward current at the base/collector interface. At the common-emitter configuration, under a constant $V_{BE}$ between 0~1.2V, $I_C$ has increased linearly with $V_{CE}$ for $V_{CE}$ < $V_{BE}$ indicating the saturation region. As the $V_{CE}$ increases further, a plateau of $I_C$ vs. $V_{CE}$ has appeared slightly at $V_{CE}{\simeq}V_{BE}$, denoting forward-active region. With further increase of $V_{CE}$, $I_C$ has kept increasing probably due to tunneling through thin Schottky barrier between B/C. Thus the current on/off ration has exhibited to be 50. To improve hot electron effects, we propose the usage of low doped Si substrate, insertion of barrier layer between B/C, or substrates with low electron affinity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.771-774
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• 2003

Passivation Ledge's device is taken possession on one-side to the Emitter in this Paper. contact used in this paper Pt as Passivation Ledge of device to use Schottky Diode which has leitmotif, It is accomplished Current Modulation that we wish to do purpose using this device. Space Charge acts as single device which is becoming Passivation to know this phenomenon. This device becomes floating as well as Punched-through. V$_{L}$ (Voltage for Ledge) = - 0.5V ~ 0.5V variable values , PD(Partially Depleted ; Λ＞0), as seeing FD(Fully Depleted ; A = 0) maximum electric current gains and Gummel Plot of I-V characteristics (V$_{L}$ = 0.1/ V$_{L}$ = -0.1 ). Becomming Degradation under more than V$_{L}$ = 0.1 , less than V$_{L}$ =-0.05 and Maximum Gain(=98.617076 A/A) value in the condition V$_{L}$ = 0.1. A Change of Modulation is electric current gains by using Schottky Diode and Extrinsic Base PN Diode of Passivation Ledge to Emitter Depletion Layer in HBT of Gummel-Poon I-V characteristics and the RF wide-band electric current gains change the Modulation of CE(Common-Emitter) amplifier description, and it had accomplished Current Gain Modulation by Ledge Bias that change in high frequency and wide bands. wide bands.s.

• 한국항행학회논문지
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• 제10권3호
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• pp.256-262
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• 2006

본 논문에서는 증폭기의 비선형 특성인 AM/AM 과 AM/PM 현상을 보상해주는 새로운 형태의 선형화기를 제안하였다. 이 선형화기는 공통 이미터 증폭기와 쇼트키 다이오드를 이미터와 접지 사이에 연결한 형태로 구성되어 있어, 쇼트키 다이오드의 접합 저항 값이 변화함에 따라 이득 증가 와 위상 확장 특성을 얻을 수 있다. 이러한 결과를 이용하여 증폭기의 비선형 특성을 개선시킬 수 있으며, 셀룰라 기지국 주파수 밴드의 증폭기를 제작하여 증폭기의 비선형 특성 개선을 확인하였다. 반송파 2톤 신호를 인가하였을 때, 주파수 간격이 1MHz에서 3차 혼변조 신호는 10.4dB 개선되었고, IS-95 CDMA 1FA 신호에서는 인접채널 전력비가 9.6dB 개선됨을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.213-216
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• 2001

The use of a thin film of indium between the ITO and the $n^{+}$-InP contact layers for InP/InGaAs HPTs was studied without degrading its excellent optical transmittance properties. ITO/$n^{+}$-InP ohmic contact was successfully achieved by the deposition of Indium and thermal annealing. The specific contact resistance of about 6.6$\times$$10^{-4}$$\Omega\textrm{cm}^2$ was measured by use of the transmission line method (TLM). However, as the thermal annealing was just performed to ITO/$n^{+}$-InP contact without the deposition of Indium between ITO and $n^{+}$-InP, it exhibited schottky characteristics. In the applications, the DC characteristics of InP/InGaAs HPTs with ITO emitter contacts was compared with that of InP/InGaAs HBTs with the opaque emitter contacts.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.415-419
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• 1999

Many bipolar logic circuit of conventional occurred problem of speed delay according to deep saturation state of vertical NPN Transistor. In order to remove minority carries of the base region at changing signal in conventional bipolar logic circuit, we made transistor which is composed of NPN transistor shortened buried layer under the Base region, PNP transistor which is merged in base, epi layer and substrate. Also the Ring-Oscillator for measuring transmission time-delay per gate was designed as well. The structure of Gate consists of the vertical NPN Transistor, substrate and Merged PNP Transistor. In the result, we fount that tarriers which are coming into intrinsic Base from Emitter and the portion of edge are relatively a lot, so those make Base currents a lot and Gain is low with a few of collector currents because of cutting the buried layer of collector of conventional junction area. Merged PNP Transistor's currents are low because Base width is wide and the difference of Emitter's density and Base's density is small. we get amplitude of logic voltage of 200mv, the minimum of transmission delay-time of 211nS, and the minimum of transmission delay-time per gate of 7.26nS in AC characteristic output of Ring-Oscillator connected Gate.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.731-736
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• 2014

An organic junction transistor with a vertical structure based on an active layer of poly(3-hexylthiophene) was fabricated by facile micro-contact printing combined with the Langmuir-Schaefer technique, without conventional e-beam or photo-lithography. Direct printing and subsequent annealing of Au-nanoparticles provided control over the thickness of the Au electrode and hence control of the electrical contact between the Au electrode and the active layer, ohmic or Schottky. The junction showed similar current-voltage characteristics to an NPN-type transistor. Current through the emitter was simply controllable by the base voltage and a high transconductance of ~0.2 mS was obtained. This novel fabrication method can be applied to amplifying or fast switching organic devices.

• 한국전자파학회논문지
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• 제19권10호
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• pp.1096-1103
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• 2008

본 논문에서는 개별 차수 혼변조 신호 발생기를 이용한 전치 왜곡 선형화기 구조를 제안하였다 혼변조 신호 발생기는 공통 에미터 증폭기의 에미터 단자에 쇼트키 다이오드를 삽입하여, 3차와 5차 혼변조 신호를 다이오드 바이어스 전압에 따라서 발생시킨다. 이렇게 만들어진 혼변조 신호는 다이오드의 직렬 궤환을 이용한 것으로, 다이오드 바이어스 제어에 따라서 혼변조 신호의 크기와 위상을 변화시킬 수 있다. 이러한 혼변조 발생기를 전치 왜곡 선형화기로 사용했을 때, 반송파 2톤 신호 인가 시 3차와 5차 혼변조 신호는 각각 13.5 dB, 0.9 dB의 개선을 보였고, 광 대역폭을 갖는 CDMA IS-95 2FA 신호를 인가하였을 경우, 중심 주파수로부터 ${\pm}0.885$ MHz, ${\pm}1.23$ MHz 떨어진 지점에서 ACLR이 각각 2.3 dB, 2.5 dB의 개선됨을 확인하였다.