1. A MOSFET made with n* poly-silicon gate has the following characteristics: Oxide thickness Xox =...

 

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1. A MOSFET made with n* poly-silicon gate has the following characteristics: Oxide thickness Xox = 500 = 50 nm Doping in Si: NA = 1016 cm-3 Interface oxide charges Q = 6.4 10 1.6 10-19 C/cm Area A = 1 cm = m s, a. Calculate the flat-band voltage VFB for this device. Hint: Since the gate is made of n*-poly- Si, assume that the gate Fermi-level is at the conduction band edge. Since Pms the magnitude of Pms in this case will be equal to: (1/q) [EF(gate) EF(silicon)] - b. Calculate the threshold voltage, VT', if the device were ideal. (This is the threshold voltage if the Oms were zero and there were no interface charges). C. Calculate the actual threshold voltage, VT, for this device taking into account Pms and the interface charges. d. Plot the high frequency CG-VG characteristics for this device. Mark important points in the graph. (Ignore the presence of Source/Drain for this particular case). e. What changes will you see if you consider the presence of source and drain? How will the high frequency CG-VG characteristics change? f. Suppose we want to increase the threshold voltage by 1.0 V (i.e., AVT = +1.0 V), calculate the number of (boron or phosphorus: choose one) ions that should be implanted into silicon. 1. A MOSFET made with n* poly-silicon gate has the following characteristics: Oxide thickness Xox = 500 = 50 nm Doping in Si: NA = 1016 cm-3 Interface oxide charges Q = 6.4 10 1.6 10-19 C/cm Area A = 1 cm = m s, a. Calculate the flat-band voltage VFB for this device. Hint: Since the gate is made of n*-poly- Si, assume that the gate Fermi-level is at the conduction band edge. Since Pms the magnitude of Pms in this case will be equal to: (1/q) [EF(gate) EF(silicon)] - b. Calculate the threshold voltage, VT', if the device were ideal. (This is the threshold voltage if the Oms were zero and there were no interface charges). C. Calculate the actual threshold voltage, VT, for this device taking into account Pms and the interface charges. d. Plot the high frequency CG-VG characteristics for this device. Mark important points in the graph. (Ignore the presence of Source/Drain for this particular case). e. What changes will you see if you consider the presence of source and drain? How will the high frequency CG-VG characteristics change? f. Suppose we want to increase the threshold voltage by 1.0 V (i.e., AVT = +1.0 V), calculate the number of (boron or phosphorus: choose one) ions that should be implanted into silicon.