• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.571-576
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• 2016

Asymmetric double gate(DG) MOSFET has the different top and bottom gate oxides thicknesses. It is analyzed the deviation of subthreshold swing(SS) and conduction path for the ratio of top and bottom gate oxide thickness of asymmetric DGMOSFET. SS varied along with conduction path, and conduction path varied with top and bottom gate oxide thickness. The asymmetric DGMOSFET became valuable device to reduce the short channel effects like degradation of SS. SSs were obtained from analytical potential distribution by Poisson's equation, and it was analyzed how the ratio of top and bottom oxide thickness influenced on conduction path and SS. SSs and conduction path were greatly influenced by the ratio of top and bottom gate oxide thickness. Bottom gate voltage cause significant influence on SS, and SS are changed with a range of 200 mV/dec for $0<t_{ox2}/t_{ox1}<5$ under bottom voltage of 0.7 V.

• 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.18 no.11
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• pp.2709-2714
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• 2014

This paper has analyzed the change of threshold voltage and conduction path for the ratio of top and bottom gate oxide thickness of asymmetric double gate MOSFET. The asymmetric double gate MOSFET has the advantage that the factor to be able to control the current in the subthreshold region increases. The analytical potential distribution is derived from Poisson's equation to analyze the threshold voltage and conduction path for the ratio of top and bottom gate oxide thickness. The Gaussian distribution function is used as charge distribution. This analytical potential distribution is used to derive off-current and subthreshold swing. By observing the results of threshold voltage and conduction path with parameters of bottom gate voltage, channel length and thickness, projected range and standard projected deviation, the threshold voltage greatly changed for the ratio of top and bottom gate oxide thickness. The threshold voltage changed for the ratio of channel length and thickness, not the absolute values of those, and it increased when conduction path moved toward top gate. The threshold voltage and conduction path changed more greatly for projected range than standard projected deviation.

• 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.19 no.7
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• pp.1617-1622
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• 2015

This paper analyzes the ratio of tunneling current for channel doping concentration of sub-10 nm asymmetric double gate(DG) MOSFET. The ratio of tunneling current for off current in subthreshold region increases in the region of channel length of 10 nm below. Even though asymmetric DGMOSFET is developed to reduce short channel effects, the increase of tunneling current in sub-10 nm is inevitable. As the ratio of tunneling current in off current according to channel doping concentration is calculated in this study, the influence of tunneling current to occur in short channel is investigated. To obtain off current to consist of thermionic emission and tunneling current, 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 channel doping concentration in sub-10 nm asymmetric DGMOSFET, specially with parameters of channel length, channel thickness, and top/bottom gate oxide thickness and voltage.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.765-768
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• 2014

본 연구에서는 비대칭 이중게이트 MOSFET의 상하단 게이트 산화막 두께 비에 대한 문턱전압 및 전도중심의 변화에 대하여 분석하고자한다. 비대칭 이중게이트 MOSFET는 상하단 게이트 산화막의 두께를 다르게 제작할 수 있어 문턱전압이하 영역에서 전류를 제어할 수 있는 요소가 증가하는 장점이 있다. 상하단 게이트 산화막 두께 비에 대한 문턱전압 및 전도중심을 분석하기 위하여 포아송방정식을 이용하여 해석학적 전위분포를 구하였다. 이때 전하분포는 가우스분포함수를 이용하였다. 하단게이트 전압, 채널길이, 채널두께, 이온주입범위 및 분포편차를 파라미터로 하여 문턱전압 및 전도중심의 변화를 관찰한 결과, 문턱전압은 상하단 게이트 산화막 두께 비에 따라 큰 변화를 나타냈다. 특히 채널길이 및 채널두께의 절대값보다 비에 따라 문턱전압이 변하였으며 전도중심이 상단 게이트로 이동할 때 문턱전압은 증가하였다. 또한 분포편차보단 이온주입범위에 따라 문턱전압 및 전도중심이 크게 변화하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.849-851
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• 2015

본 연구에서는 비대칭 이중게이트 MOSFET의 상하단 게이트 산화막 두께 비에 대한 문턱전압이하 스윙 및 전도중심의 변화에 대하여 분석하고자한다. 문턱전압이하 스윙은 전도중심에 따라 변화하며 전도중심은 상하단의 산화막 두께에 따라 변화한다. 비대칭 이중게이트 MOSFET는 상단과 하단의 게이트 산화막 두께를 다르게 제작할 수 있어 문턱전압이하 스윙의 저하 등 단채널효과를 감소시키기에 유용한 소자로 알려져 있다. 본 연구에서는 포아송방정식의 해석학적 해를 이용하여 문턱전압이하 스윙을 유도하였으며 상하단의 산화막두께 비가 전도중심 및 문턱전압이하 스윙에 미치는 영향을 분석하였다. 결과적으로 문턱전압이하 스윙 및 전도중심은 상하단 게이트 산화막 두께 비에 따라 큰 변화를 나타냈다. 또한 채널길이 및 채널두께, 상하단게이트 전압 그리고 도핑분포함수의 변화에 따라 문턱전압이하 스윙 및 전도중심은 상호 유기적으로 변화하고 있다는 것을 알 수 있었다.