• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.6-11
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• 2000

In this paper, suggesting a new linearly -graded depletion edge approximation, the current-voltage characteristics of an n-type short-channel GaAs MESFET device has been analyzed by solving the two dimensional Poisson's equation in the depletion region. In this model, the expressions for the threshold voltage, the source and the drain ohmic resistance, and the drain current were derived. As a result, typical Early effect of a short channel device was shown and the ohmic voltage drop by source and drain contact resistances could be explained. Furthermore our model could analyze both the short-channel device and the long-channel device in a unified manner.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.165-168
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• 2005

In this paper, we examined channel charge which occurs in electron accumulation after electron velocity saturation. Generally, short gate GaAs MESFET show, saturated electron velocity leading to current satulation. When electron velocity is saturated, deletion layer is still open channel and it plays a key role in deciding saturation current mode we proposed channel charge model in channel after electron velocity saturation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.21-28
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• 2008

In this paper, we suggest an analytical model that can derive the I-V characteristics in the saturation region of a short channel GaAs MESFET. Instead of the pinch-off concept that has been used in the conventional models we can derive the two-dimensional potential in the depletion region in order that the velocity saturation region cannot be pinched-off and the current continuity condition can be satisfied. Obtained expression for the velocity saturation length is expressed in terms of the total channel length, channel doping density, gate voltage, and drain voltage. Compared with the conventional channel length shortening models, the present model seems to be considerably accurate and more reasonable in explaining the Early effect.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.25-32
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• 2005

In this paper, it is attempted to provide a unified explanation for typical short channel GaAs MESFET’s and SOI-structured Si JFET's behaviors such as: i) drain voltage-induced threshold voltage roll-off, ii) finite output ac resistance beyond the saturation, and iii) weak dependence of the drain saturation current on the channel length. Replacing the conventional GCA with a new assumption that is suggested in order to include the longitudinal field variation, and taking into account the channel current continuity and the field-dependent mobility, we can derive the two-dimensional potential in both depletion region and undepleted conducting channel. Obtained expressions for the threshold voltage and the drain current will be considerably accurate over the entire operating region. Moreover, in comparison with the conventional channel length shortening models, our model seems to be more reasonable in explaining the Early effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.793-799
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• 2006

In this paper, the gate leakage current is first calculated using the experimental method between gate and drain by opening source electrode. the gate to drain current has been obtained with ground source. The difference between two currents has been tested and proves that the electric field generated by channel charge effect against the image force lowering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.52-55
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• 2004

In this paper, we examined channel charge which occurs in electron accumulation after electron velocity saturation. Generally, short gate GaAs MESFET show, saturated electron velocity leading to current salutation. When electron velocity is saturated, deletion layer is stil open channel and it play a key role in deciding saturation current mode we proposed channel charge model in channel after electron velocity saturation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.15-30
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• 2004

In this paper, an analytical modeling for the dark and photo-current characteristics of a buried-gate short- channel GaAs MESFET is presented. The presented model shows that the increase of drain current under illumination is largely due to not the increase of photo-conductivity in the neutral region but the narrowing effect of the depletion layer width. The carrier density profile within the neutral region is derived from solving the carrier continuity equation one-dimensionally. In deriving the photo-generated current, we assume that the photo-current is compensated with the thermionic emission current at the gate-channel interface. Moreover, the two-dimensional Poisson's equation is solved by taking into account the drain-induced longitudinal field effect. In conclusion, the proposed model seems to provide a reasonable explanation for the dark and photo current characteristics in a unified manner.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.1
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• pp.40-50
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• 2011

A two-dimensional (2D) analytical model for the potential distribution and threshold voltage of short-channel ion-implanted GaAs MESFETs operating in the sub-threshold regime has been presented. A double-integrable Gaussian-like function has been assumed as the doping distribution profile in the vertical direction of the channel. The Schottky gate has been assumed to be semi-transparent through which optical radiation is coupled into the device. The 2D potential distribution in the channel of the short-channel device has been obtained by solving the 2D Poisson's equation by using suitable boundary conditions. The effects of excess carrier generation due to the incident optical radiation in channel region have been included in the Poisson's equation to study the optical effects on the device. The potential function has been utilized to model the threshold voltage of the device under dark and illuminated conditions. The proposed model has been verified by comparing the theoretically predicted results with simulated data obtained by using the commercially available $ATLAS^{TM}$ 2D device simulator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.169-179
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• 1999

In this paper, a GaAs MESFET single-ended resistive mixer with high linearity and isolation is designed. The bias voltage of this mixer is applied only gate of GaAs MESFET to use the channel resistance. The LO is applied the gate and the RF is applied the drain through 7-pole hairpin bandpass filter to obtain the proper isolation thru LO-RF. The IF is extracted from the source with short circuit and lowpass filter. Using extracted equivalent circuits for LO and RF, conversion loss is calculated and compared with result of harmonic balance analysis. Measured conversion loss of this S-band down converter mixer is 8.2~10.5dB by considering the measured 3.0~3.4dB RF 7-pole hairpin bandpass filter loss and IP3in is 26.5dBm at Vg=-0.85~-1.0V in distortion performance.