• 전자공학회논문지A
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• 제31A권9호
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• pp.104-113
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• 1994

We have fabricated n-p-n HBTs using 3-inchAlgaAs/GaAs hetero structure epi-wafers grown by MBE. DC and AC characteristics of HBT devices were measured and analyzed. For HBT epi-structure, Al composition of emitter was graded in the region between emitter cap and emitter. And base layer was designed with concentration of 1${\times}10^{19}/cm^{3}$ and thickness of 50nm, and Be was used as the p-type dopant. Principal processes for device fabrication consist of photolithography using i-line stepper, wet mesa etching, and lift-off of each ohmic metal. The PECVD SiN film was used as the inslator for the metal interconnection. HBT device with emitter size of 3${\times}10{\mu}m^{2}$ resulted in cut-off frequency of 35GHz, maximum oscillation frequency of 21GHz, and current gain of 60. The distribution of the ideality factor of collector and base current was very uniform, and the average values of off-set voltage and current was very uniform, and the average values of off-set voltage and current gain were 0.32V and 32 within a 3-inch wafer.

• 한국재료학회지
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• 제13권7호
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• pp.465-472
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• 2003

Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au ohmic contacts to n-type InGaAs were investigated for applications to AlGaAs/GaAs HBT emitter ohmic contacts. In the Pd/Ge/Ti/Pt ohmic contact minimum specific contact resistivity of $3.7${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by rapid thermal annealing at $^400{\circ}C$/10 sec. In the Pd/Ge/Ti/Au ohmic contact, minimum specific contact resistivity of $1.1${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by annealing at 40$0^{\circ}C$/10 sec but the ohmic performance was degraded with increasing annealing temperature due to the reaction between the ohmic contact materials and the InGaAs substrate. However, non-spiking planar interface and relatively good ohmic contact (high-$10^{-6}$ /$\Omega$$\textrm{cm}^2$) were maintained after annealing at $450^{\circ}C$/10 sec. Therefore, these thermally stable ohmic contact systems are promising candidates for compound semiconductor devices. RF performance of the AlGaAs/GaAs HBT was also examined by employing the Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au systems as emitter ohmic contacts. Cutoff frequencies were 63.5 ㎓ and 65.0 ㎓, respectively, and maximum oscillation frequencies were 50.5 ㎓ and 51.3 ㎓, respectively, indicating very successful high frequency operations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.401-404
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• 1998

Recently, InGaP/GaAs HBTs have been much interested as a potential replacement for AlGaAs/GaAs HBTs because of their superior device and material properties. In this paper, DC characteristics of InGaP/GaAs HBTs and the temperature dependance as well as the reliability were investigated comparing with AlGaAs/GaAs HBTs. As a results InGaP/GaAs HBTs produced the superior performance to AlGaAs/GaAs HBTs.

• 전자공학회논문지A
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• 제33A권12호
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• pp.39-46
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• 1996

In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.461-464
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• 1998

Self-aligned AlGaAs/GaAs HBTs with the emitter area of 1.5*10.mu.$m^{2}$ were fabricated usng $WN_{x}$ as emitter metal. Their DC and RF characteristics were investigated. The common emitter current gain was 45 at $J_{c}$ = 6*$10^{4}$A/$cm^{2}$. From the Gummel plot, the ideality factors of $I_{c}$ and $I_{B}$ were 1.18 and 1.70, respectively. Emitter and base resistance were extracted from voltage drop region in gummel plot, and their values were 5.3.ohm. and 38.2.ohm.. The extrapolated $f_{T}$ = 72GHz and $f_{max}$ = 81GHz were obtained at $V_{CE}$ = 2V.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.52-52
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• 2009

In this work, we demonstrate the modelling and simulation of the AlGaAs/GaAs quantum-well based light emitting transistor(LET). Based on the experimental and theoretical model, we have compared between a heterojunction bipolar transistor(HBT) structure with quantum wells in the base region and a HBT without quantum wells in the base region. For the purpose of optimizing device design, several analytic and numerical studies have been presented.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.10-12
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• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs

• 전자공학회논문지D
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• 제34D권3호
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• pp.52-59
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• 1997

Design and performance of principal four ICs for the 10-Gb/s optical communication system are presented. AlGaAs/GaAs HBTs are basic devices to implement a laser diode driver, apre-amplifier, and a limiting amplifier, and GaInP/GaAs HBTs are used for an AGC amplifier. We fbricated 11.5-GHz LD driver, a pre-amplifier, and a limiting amplifier, an dGaInP/GaAs HBTs are used for an AGC amplifier. We fabricated LD deriver, 10.5 GHz pre amplifier, 7.2 GHz AGC amplifier, and 10.3 GHz limiting amplifier, optimized circuit design and the stabilized MMIC fabrication process.

• 전자공학회논문지D
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• 제34D권11호
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• pp.30-36
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• 1997

AlGaAs/GaAs HBTs are developed well enough to be commercialized as an active device in optical transmission system, but there remains the unanswered questions about reliability. In this paper we applied the reverse constant current stress at the high voltage in avalanche region for a long time to find out a new degradation mechanism of junctrion I-V. The unction off-set voltage at which the current vanishes to zero was shifted to the negative direction of applied bias due to the increment of leakage current as the stress time increases. It was identified that the degradation was induced by the hot carriers which were generated at space charge region and trapped at the interface between GaAs base and the passivation nitride enhancing the electric field across the nesa edge.

• 한국진공학회지
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• 제11권1호
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• pp.43-49
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• 2002

N형 InGaAs에 대한 Pd/Ge/Pd/Ti/Au 오믹 접촉의 급속 열처리 조건에 따른 오믹 특성을 조사하였다. $450^{\circ}C$까지의 열처리에 의해 우수한 오믹 특성을 나타내어 $400^{\circ}C$/10초의 급속 열처리 후에 최저 $1.1\times10^{-6}\Omega\textrm{cm}^2$의 접촉 비저항을 나타내었다. $425^{\circ}C$ 이상의 열처리 후에 접촉 비저항이 점점 증가하여 $450^{\circ}C$에서는 오믹 재료와 InGaAs의 반응에 의해 오믹 특성의 열화가 나타났다. 그러나 high-$10^{-6}\Omega\textrm{cm}^2$ 정도의 비교적 우수한 오믹 특성을 유지하였고, 양호한 표면 및 계면이 얻어져 화합물 반도체 소자에의 응용 가능성이 충분한 것으로 판단된다.