chapter2-device01

# Digital ic 2 device attention velocity position t gs

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Digital IC 2: Device Attention : velocity position ] ) ( [ ) ( T gs x o i V x V V C x Q Charge per unit area: W x Q x v I i n D ) ( ) ( dx dV x E x v n n n ) ( ) ( W V x V V C dx dV I T gs x o n D ] ) ( [ DS V T gs x o n L D WdV V x V V C dx I 0 0 ] ) ( [ s . /v cm 1800 = μ s, . /v cm 3800 = μ 2 p 2 n ) ( 2 ) ( ) ( 2 DSAT DSAT DSAT T GS ox n DSAT GT ox sat D V V V V V L W C V V W C I 60/74

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Digital IC 2: Device Velocity Saturation c sat c c n v v z z z z z z z for for 1 x (V/μm) x c = 1.5 u n ( m / s ) u sat = 10 5 Constant mobility (slope = μ) Constant velocity The critical field depends upon the doping levels and the vertical electrical field applied(1-5V/um) 61/74
Digital IC 2: Device Velocity Saturation ) ( 2 ) ( 2 ) ( ) ( 1 2 2 DS DS DS T GS ox n DS DS T GS c DS ox n D V V V V V L W C V V V V L W L V C I x c L ξ V + 1 1 = κ(V) 62/74

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Digital IC 2: Device Velocity Saturation ) ( 2 ) ( ) ( 2 DSAT DSAT DSAT T GS ox n DSAT GT ox sat D V V V V V L W C V V W C I GT GT DSAT V V V ) ( 63/74
Digital IC 2: Device Perspective I D Long-channel device Short-channel device V DS V DSAT V GS - V T V GS = V DD 64/74

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Digital IC 2: Device I D versus V GS 0 0.5 1 1.5 2 2.5 0 1 2 3 4 5 6 x 10 -4 V GS (V) I D (A) 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 2.5 x 10 -4 V GS (V) I D (A) quadratic quadratic linear Long Channel Short Channel 65/74
Digital IC 2: Device Another two assumptions c sat c c n v v z z z z z z z for for 1 L V V V V V c GT GT GT GT DSAT x 1 ) ( c sat c n v v z z z z z for for n SAT c V DSAT Lv L V GT x 66/74

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