Problem 3 (25 points) Consider a MOS capacitor with p polysilicon gate and p-type silicon substrate with NA 1016 cm3. Ef- Ev in the polysilicon gate. Assume the following parameters: I200A, , 1.5x10°...
A MOS capacitor is made on n-type silicon with oxide thickness of 50 A, a positive interface charge of 5 x 1010 cm2 and a uniform positive oxide charge of density p- 2 x 106 cm3 throughout the oxide. The substrate is doped with Na-101" cm3 and the gate is polysilicon doped with boron just to the edge of degeneracy (p+ poly, Ef -Ev). a. Calculate the flat band voltage VB and the threshold voltage Vr b. Sketch the charge...
Section B (total 60 marks for section B) B1 a) An MOS capacitor has a p-type semiconductor substrate doped with an impurity concentration of 1018 cm3. Assume a poly-Si material is used for the gate. Draw a diagram of the capacitor structure showing material types and an energy band diagram it is in thermal equilibrium. (10 marks) b) Given an MOS capacitor with a p-type semiconductor substrate and poly-Si material as gate (in part a), what is the meaning of...
Problem3: Consider a MOS capacitor maintained at T 300K with the following characteristics: Assume Esi 1.9,x 3.9,8.85 x 10-14 F/cm, and n 1.5 x 1010cm3 . Gate material is n+ poly-silicon . Total negative oxide charge of 5x 1011q C/cnm2 . Substrate is n-type Si, with doping concentration 1x1016 cm3 Oxide thickness 5 nm . The electron affinity for Si is 4.03eV? a) Draw the band diagram at equilibrium. b) From part (a). What is the substrate (bulk) condition at...
Consider an n-channel Silicon MOS system with a substrate resistivity of 10 0-cm and with a polycrystalline gate. Assume that the polysilicon gate is doped with boron atoms to a density of 1x1019 cm and that the silicon dioxide is 50 nm-thick. The channel is not biased except from the gate (Vc= VB = 0). (i) Accurately sketch the band diagram identifying flatband voltage, surface potential at inversion, depletion width at inversion, and charges at inversion. Tabulate these parameters. (ii)...
Problem 3: Consider a MOS capacitor maintained at T= 300K with the following characteristics: Assume s 11.9, ox 3.9, 8.85x 10-1 F/cm, and n 1.5 x 1010cm3 Gate material is n poly-silicon Total negative oxide charge of 5x 1011q C/cm . Substrate is n-type Si, with doping concentration 1 x1016 cm-3 Oxide thickness 5 nmm The electron affinity for Si is 4.03eV? e) What is the flat capacitance? f) What is the depletion region width? g) What is the potential...
Problem 1. An n-channel MOS transistor is fabricated with the following specifications: Substrate is a p-type silicon with doping concentration NA=2x1015 cm-3 . The SiO2 gate thickness is 200 Å. Effective interface charges Qi=6.5x10-9 col/cm2. Work function difference between gate conductor and silicon substrate qфms=-0.95 eV. Calculate the following: a. Maximum depletion width, with respect to ground b. Gate capacitance per unit area, Ci c. Flat-band voltage, VFB d. Threshold voltage, VT.
Consider a modern PMOS capacitor with an Pt gate[1](ΦM= 5.1 eV) and n-type silicon substrate (ND= 1018cm-3). (a) The desired oxide capacitance is 2.5 µF/cm2. Calculate the SiO2thickness and the HfO2thickness that can enable this capacitance. If the thickness of a monolayer of SiO2is 3.5 Å, how many monolayers is that? What is the advantage of using HfO2? (b) Calculate the substrate work function and the flatband voltage of the capacitor. Now qualitatively (but carefully) sketch the band diagrams under...
6. A MOS system has an n+ polysilicon gate and a p-type silicon substrate doped to N. =10cm. Assume there is an oxide surface charge density (Q,/q) = 100cm 2. Design the oxide thickness so that V1 = 0.5 V (no bias is applied between the channel and substrate). Answer: x 58.5 nm OX
Problem 5: The gate capacitance vs. gate voltage characteristic of a p+ poly-Si gated MOS capacitor of area 1x10"cm', is as shown: Assume Esi = 11.9, Eox-39,E,-8.85 × 10-14 F/on, and nl = 1.5 x 1010 cm3 Co [Farads] 3.45x1011 >Va [Volts] 1.0 0.3 (a) Is the semiconductor (silicon) substrate doped n-type or p-type? Explain briefly. (b) Is the measurement frequency low or high? Explain briefly. (c) What is the thickness of the gate oxide (SiO2), xo? (d) Estimate the...
Q1 Which of the following is true for a MOS capacitor with a P-type body? Select one: a. The charge in the inversion layer stays approximately constant as the gate voltage is increased above the threshold voltage b. The charge in the depletion region is proportional to the square root of the depletion region width, assuming that the body is uniformly doped c. In inversion, the total charge is equal to the sum of the charge in the depletion region...