• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1399-1404
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• 2015

This paper analyzed the phenomenon of drain induced barrier lowering(DIBL) for the ratio of channel length vs. thickness of asymmetric double gate(DG) MOSFET. DIBL, the important secondary effect, is occurred for short channel MOSFET in which drain voltage influences on potential barrier height of source, and significantly affects on transistor characteristics such as threshold voltage movement. The series potential distribution is derived from Poisson's equation to analyze DIBL, and threshold voltage is defined by top gate voltage of asymmetric DGMOSFET in case the off current is 10^-7 A/m. Since asymmetric DGMOSFET has the advantage that channel length and channel thickness can significantly minimize, and short channel effects reduce, DIBL is investigated for the ratio of channel length vs. thickness in this study. As a results, DIBL is greatly influenced by the ratio of channel length vs. thickness. We also know DIBL is greatly changed for bottom gate voltage, top/bottom gate oxide thickness and channel doping concentration.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2621-2626
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• 2013

This paper has presented the potential distribution for asymmetric double gate(DG) MOSFET, and sloved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET where both the front and the back gates are tied together is three terminal device and has the same current controllability for front and back gates. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine current controllability for front and back gates. To approximate with experimental values, we have used the Gaussian function as doping distribution in Poisson equation. The potential distribution has been observed for gate bias voltage and gate oxide thickness and channel doping concentration of the asymmetric DGMOSFET. As a results, we know potential distribution is greatly changed for gate bias voltage and gate oxide thickness, especially for gate to increase gate oxide thickness. Also the potential distribution for source is changed greater than one of drain with increasing of channel doping concentration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.691-694
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• 2013

This paper has presented the potential distribution for asymmetric double gate(DG) MOSFET, and sloved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET where both the front and the back gates are tied together is three terminal device and has the same current controllability for front and back gates. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine current controllability for front and back gates. To approximate with experimental values, we have used the Gaussian function as charge distribution in Poisson equation. The potential distribution has been observed for gate bias voltage and gate oxide thickness and channel doping concentration of the asymmetric DGMOSFET. As a results, we know potential distribution is greatly changed for gate bias voltage and gate oxide thickness, especially for gate to increase gate oxide thickness. Also the potential distribution for source is changed greater than one of drain with increasing of channel doping concentration.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.581-586
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• 2015

This paper has analyzed the variation of subthreshold swing for the ratio of channel length and thickness for asymmetric double gate MOSFET. The asymmetric double gate MOSFET has the advantage that the factors to control the short channel effects increase since top and bottom gate structure can be fabricated differently. The degradation of transport property due to rapid increase of subthreshold swing can be specially reduced in the case of reduction of channel length. However, channel thickness has to be reduced for decrease of channel length from scaling theory. The ratio of channel length vs. thickness becomes the most important factor to determine subthreshold swing. To analyze hermeneutically subthreshold swing, the analytical potential distribution is derived from Poisson's equation, and conduction path and subthreshold swing are calculated for various channel length and thickness. As a result, we know conduction path and subthreshold swing are changed for the ratio of channel length vs. thickness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1925-1930
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• 2014

This paper has analyzed the relation of conduction path and subthreshold swing for doping profile in channel of asymmetric double gate(DG) MOSFET. Since the channel size of asymmetric DGMOSFET is greatly small and number of impurity is few, the high doping channel is analyzed. The analytical potential distribution is derived from Possion's equation, and Gaussian distribution function is used as doping profile. The conduction path and subthreshold swing are derived from this analytical potential distribution, and those are investigated for variables of doping profile, projected range and standard projected deviation, according to the change of channel length and thickness. As a result, subthreshold swing is reduced when conduction path is approaching to top gate, and that is increased with a decrease of channel length and a increase of channel thickness due to short channel effects.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.741-744
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• 2014

This paper has analyzed threshold voltage roll-off for bottom gate voltages of asymmetric double gate(DG) MOSFET. Since the asymmetric DGMOSFET is four terminal device to be able to separately bias for top and bottom gates, the bottom gate voltage influences on threshold voltage. It is, therefore, investigated how the threshold voltage roll-off known as short channel effects is reduced with bottom gate voltage. In the pursuit of this purpose, off-current model is presented in the subthreshold region, and the threshold voltage roll-off is observed for channel length and thickness with a parameter of bottom gate voltage as threshold voltage is defined by top gate voltage that off-currnt is $10^{-7}A/{\mu}m$ per channel width. As a result to observe the threshold voltage roll-off for bottom gate voltage using this model, we know the bottom gate voltage greatly influences on threshold voltage roll-off voltages, especially in the region of short channel length and thickness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1143-1148
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• 2014

This paper has analyzed the change of subthreshold swing for doping distribution function of asymmetric double gate(DG) MOSFET. The basic factors to determine the characteristics of DGMOSFET are dimensions of channel, i.e. channel length and channel thickness, and doping distribution function. The doping distributions are determined by ion implantation used for channel doping, and follow Gaussian distribution function. Gaussian function has been used as carrier distribution in solving the Poisson's equation. Since the Gaussian function is exactly not symmetric for top and bottome gates, the subthreshold swings are greatly changed for channel length and thickness, and the voltages of top and bottom gates for asymmetric double gate MOSFET. The deviation of subthreshold swings has been investigated for parameters of Gaussian distribution function such as projected range and standard projected deviation in this paper. As a result, we know the subthreshold swing is greatly changed for doping profiles and bias voltage.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.748-751
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• 2014

This paper has analyzed threshold voltage movement for channel doping concentration of asymmetric double gate(DG) MOSFET. The asymmetric DGMOSFET is generally fabricated with low doping channel and fully depleted under operation. Since impurity scattering is lessened, asymmetric DGMOSFET has the adventage that high speed operation is possible. The threshold voltage movement, one of short channel effects necessarily occurred in fine devices, is investigated for the change of channel doping concentration in asymmetric DGMOSFET. The analytical potential distribution of series form is derived from Possion's equation to obtain threshold voltage. The movement of threshold voltage is investigated for channel doping concentration with parameters of channel length, channel thickness, oxide thickness, and doping profiles. As a result, threshold voltage increases with increase of doping concentration, and that decreases with decrease of channel length. Threshold voltage increases with decrease of channel thickness and bottom gate voltage. Lastly threshold voltage increases with decrease of oxide thickness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.992-997
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• 2016

This paper analyzes the deviation of tunneling current for the ratio of top and bottom gate oxide thickness of short channel asymmetric double gate(DG) MOSFET. The ratio of tunneling current for off current significantly increases if channel length reduces to 5 nm. This short channel effect occurs for asymmetric DGMOSFET having different top and bottom gate oxide structure. The ratio of tunneling current in off current with parameters of channel length and thickness, doping concentration, and top/bottom gate voltages is calculated in this study, and the influence of tunneling current to occur in short channel is investigated. The analytical potential distribution is obtained using Poisson equation and tunneling current using WKB(Wentzel-Kramers-Brillouin). As a result, tunneling current is greatly changed for the ratio of top and bottom gate oxide thickness in short channel asymmetric DGMOSFET, specially according to channel length, channel thickness, doping concentration, and top/bottom gate voltages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.805-810
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• 2016

The dependence of drain induced barrier lowering(DIBL) is analyzed for doping concentration in channel of asymmetric double gate(DG) MOSFET. The DIBL, the important short channel effect, is described as lowering of source barrier height by drain voltage. The analytical potential distribution is derived from Poisson's equation to analyze the DIBL, and the DIBL is observed according to top/bottom gate oxide thickness and bottom gate voltage as well as channel doping concentration. As a results, the DIBL is significantly influenced by channel doping concentration. DIBL is significantly increased by doping concentration if channel length becomes under 25 nm. The deviation of DIBL is increasing with increase of oxide thickness. Top and bottom gate oxide thicknesses have relation of an inverse proportion to sustain constant DIBL regardless channel doping concentration. We also know the deviation of DIBL for doping concentration is changed according to bottom gate voltage.