The electric field distribution in an MOS capacitor is shown. The flatband voltage VFB = 0. (a) Is the substrate p-type or n-type? Give your reason. (b) Determine the oxide dielectric constant, Ko. (c) Determine the oxide voltage, the surface potential, and the gate voltage. Assume the substrate is grounded. (d) Determine the oxide capacitance (in F/cm2) (e) Determine the substrate doping density (in cm−3) (f) Draw the potential to scale, i.e. , quantitatively. Use Ks = 12.
![A MOS capacitor is made from Si. When VG is applied to the gate of the capacitor, the band diagram looks as shown below. Answer the questions that follow. (a) Is the applied gate voltage VG positive or negative? Explain. (b) Is the semiconductor p-type or n-type? What is the doping concentration? (c) Calculate the number of electrons and holes in the bulk of the semiconductor. (d) Calculate the number of electrons and holes near the surface of the semiconductor. (e) Is the semiconductor under depletion, inversion or in flat-band condition? (f) If we define the electrostatic potential, φ(x) = (1 /q) [Ei(bulk) − Ei(x)], plot φ(x) versus x. (g) Plot the charge density as a function of x. Identify in your plot which are mobile charges and which are ionized donors or acceptors.](https://www.doubtrix.com/uploads/editor/6969718029XlgEeYoZyk.png)