• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.794-803
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• 1987

In this paper, the SPICE 2.G6 JFET subroutine and other related subroutines are modified for circuit simulation of GaAs MESFET IC's. The hyperbolic tangent model is used for the drain current-voltage characteristics of GaAs MESFET's and derived channel-conductance and drain-conductance model from the above current model are implemented into small-signal model of GaAs MESFET's. And, device capacitance model which consider after-pinch-off state are modified, and device charge model for SPICE 2G.6 are proposed. The result of modification is shown to be suitable for GaAs circuit simulator, showing good agreement with experimetal results. Forthermore the DC convergence of this paper is better than that of SPICE 2.G JFET subroutine. GaAs MESFET model in this paper is applied for both depletion mode GaAs MESFET and enhancement-mode GaAs MESFET without difficulty.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1736-1742
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• 1989

In this thesis, to verify input-output characteristics of GaAs MESFET, light is illuminated to C-band oscillator which already designed and manufactured, thus input-output variation of GaAs MESFET is to be shown. Experimental results of two kinds of optical effects, optical tuning and opticla switching, of GaAs MESFET Oscillators are presented. For optical tuning, the Oscillation frequency decreases with optical illumination and the Oscillator power output generally increases with optical illumination, the increase being around 1 to 3 dBm at 1mW/mm\ulcornerlight intensity. While the DC-lingt illuminated Oscillator response data provide information of the optical senditivity of GaAs-MESFET Oscillators. Pulse-light illuminated transient response data can be invoked to understand the detailed optical-electrical interaction mechanisms response. Thus, it is shown that direct control of micro-devices is realisable, if we use optical effect of GaAs semiconductor compound.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.82-85
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• 2000

The less sensitive structure to the surface effect has been presented utiliting an undoped GaAs layer on the n-GaAs channel. The undoped layer has been found to be effective to supress the frequency dispersion phenomena caused by a surface trapping effect and to raise the MESFET's performance. The gate structure, with an undoped layer underneath the gate metal has been found to be effective to improve the breakdown voltage. GaAs MESFETS with different physical structures are fabricated and DC characteristics are measued. GaAs MESFET's are fabricated on epi-wafers which have an undoped GaAs layer in between n+ and n GaAs layers grown by MBE.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.2025-2031
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• 1989

In this paper, using optical effect of characteristics of GaAs compound, two potential application of optical controlled GaAs MESFET are demonstrated` detector, microwave amplifier gain control. These lead to the possibility of the interaction with optical devices. The preliminary experiments show the light induced voltage, the increase in the drain currnet and the change in the microwave scattering parameters of GaAs MESFET under optical illumination(He-Ne laser). And imcrowave amplifier gain is round to be varied with changing in intensity of optical illumination.

• Journal of the Korean Institute of Telematics and Electronics
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• v.13 no.5
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• pp.1-8
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• 1976

Microwave GaAs Metal Semiconductor Field effect Transistors (MESFET) with the gate-length of two micrometers are investigated. The scattering parameters of the transistors have been measured from 1GHz to 2GHz by Hp8545 Automatic network analyzer. From the measured data, an equivalent circuit is established which consists of an ntrinsic and. extrinsic transistor elements. In this paper, GaAb MESFET Amplifier is used in conjunction with conventional microstrip techniques to match into a 50 ohms high input/output impedances system. We found that Power gain is less than 8dB and VSWR is less than 1.5 in L-Band.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1321-1323
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• 1998

We investigated drain leakage current in GaAs power MESFET. The device we studied by 20 simulation has a $1000{\AA}$ thick AlGaAs buffer layer under n-GaAs active layer. The calculation shows that the leakage current through GaAs substrate is significantly reduced by the buffer layer.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.3
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• pp.41-47
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• 1999

Ion implanted GaAs MESFET with low resistive layer was fabricated using Si diffusion into GaAs from SiN. During the thermal annealing at 95$0^{\circ}C$ for 30s, Si diffused into ion implanted region of GaAs from SiN and they formed low resistive layer of 350$\AA$ thickness. The diffusion of Si decreased the sheet resistance of source and drain region from 1000$\Omega$/sq. to 400$\Omega$/sq. and the AuGe/Ni/Au ohmic contact resitivity from 2.5$\times$10sub -6$\Omega$-cmsup 2 to $1.5\times$10sup -6$\Omega$-cmsup 2. The fabricated lum gate length MESFET with Si diffused surface layer shows the transconductance of 360ms/mm, 8.5dB of associated gain and 3.57dB of minimum noise figure at 12GHz. These performances are better than that of MESFET without Si diffused layer.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.789-794
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• 1986

The current-voltage characteristics of ion-implanted GaAs MESFET's have been simulated by using the velocity saturation model. Using this model, a MESFET with threshold voltage of -0.5V and transconductance of 460 mS/mm is designed. To implement high transconductance MESFET's, low energy ion-implantation (20 keV) and RTP(Rapid Thermal Process) activation ($575^{\circ}C$, 5sec) processes are required.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.3
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• pp.210-224
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• 2006

A new analytical model for the static I-V characteristics of GaAs MESFET’s under optically controlled conditions in both linear and saturation region is presented in this paper. The novelty of the model lies in characterizing both photovoltaic (external, internal) and photoconductive effects. Deep level traps in the semi insulating GaAs substrate are also included in this model. Finally, effect of backgate voltage on I-V characteristics is explained analytically for the first time in literature. Small signal parameters of GaAs MESFET are derived under both dark and illuminated conditions. Some of the results are compared with reported experimental results to show the validity of the proposed model. Since accurate dc modeling is the key to accurate ac modeling, this model is very useful in the designing of photonic MMIC’s and OEIC’s using GaAs MESFET.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1071-1083
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• 1991

In this paper, we describe the design and realization of optical preamplifier with InGaAs APD and GaAs MESFET. Optical preamplifier which is three stage trans-impedance circuit is analyzed in detail and realized in microstrip circuits. With the kmowledge of the InGaAs, GaAs MESFET and BJT, the performance of the optical is predicted by computer simulation and the theoretical predictions are compared with the experimental results. The designed hybrid MIC optical preamplifier exhibits a bandwith of 380MHz and a receiver sensitivity of -40. 6dBm at $1.55{\mu}m$ wavelength when operating at 565Mb/s with BER of $10^{-9}$.