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Unformatted text preview: ECE 440 Homework XIV Spring 2006 1. Redraw Figure 612 of band diagrams for the ideal MOS structure in an ntype silicon at (a) thermal equilibrium (b) electron accumulation (c) electron depletion and (d) strong inversion. Also, in the drawing show a simple circuit illustrating how the biasing is applied in each case. 2. For an ideal MOS structure, the SiO 2 thickness is 300 , and the substrate is doped with 2x10 16 /cm 3 acceptors. Determine the threshold voltage, V T , required to achieve strong inversion and find the electric field in the oxide when the applied bias V=V T . Repeat for a different MOS where the SiO 2 thickness is 40 but the substrate doping is the same. For an ideal MOS, the equation to determine threshold voltage is (633) F i d s i d T C Q C Q V 2 + = + = So we need to calculate the three unknown quantities. 0.365V ln = = = i A F i F n N q kT E E 2 7 8 14 10 15 . 1 10 300 10 85 . 8 9 . 3 cm F d C i i...
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 Spring '11
 Leburton

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