For electron affinity of semiconductor materials, please refer to the material parameters table in the appendix of your textbook. For metal work functions, you can find the values in Table 3.2.1 of...

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For electron affinity of semiconductor materials, please refer to the material parameters table in the appendix of your textbook. For metal work functions, you can find the values in Table 3.2.1 of the textbook. 1. Schottky Capacitance The Schottky junction can be used as a voltage tuned capacitance in an integrated circuit. (a) Make a plot of capacitance per unit area as a function of voltage for a Schottky capacitor formed from an Ag contact on n silicon doped to Nd = 1 × 1018/cm3 . (b) Make a plot of the capacitance per unit area as a function of doping for a Schottky capacitor formed from an Ag contact on n silicon at zero applied voltage. (c) Describe in detail how would you design a Schottky capacitor for maximum voltage sensitivity. Your design choices should include metals (Ag, Al, Au, Cr, Ni, Pt and W) and semiconductors (silicon and GaAs) as well as doping. (d) Describe in detail how would you design a Schottky capacitor for maximum voltage range. Your design choices should include metals (Ag, Al, Au, Cr, Ni, Pt and W) and semiconductors (silicon and GaAs) as well as doping. 2. Ohmic Contacts In Figure 1, the electron affinities for GaAs, Si and Ge are all seen to be large enough that the barrier energy EB = EM − χ is less than the band gap for both Si and GaAs in all the cases listed in Figure 2. (a) Calculate how far below the conduction band edge the Fermi energy must be in order that the Fermi level of the semiconductor be at same level as the Fermi energy of the metal for Au on n-Si. (b) Calculate the doping level for the Femi level to have the value of the previous part. (c) Describe in some detail the implications of the Fermi levels of the semiconductors lining up both in the flat band model and after connection. Draw a resulting band level diagram for the resulting metal on semiconductor junction. 1 Figure 1: A table of material parameters taken from the appendix of Van Zeghbroeck. The electron affinites are of especial interest in the problem in question. Figure 2: Work functions for some metals and associated barrier heights with germanium, silicon and gallium arsenide all taken from table 3.2.1 in Van Zeghbroeck. 3. Schottky Diode Current The difference between the Schottky drift/diffusion current and Schottky thermionic current is the difference between the drift velocity at the contact and the Richardson velocity. This difference is dependent on mobility, doping (through the maximum electric field at the barrier) and temperature as well as effective mass of the electron. In the following, consider a Au contact. (a) Using Nd = 1 × 1016, compare these velocities for n Si and n GaAs for T=300◦K. (b) Find the value of the temperature at which the values become equal. (c) Find the values of doping at which the values become equal at room temperature.
Answered 3 days AfterMar 16, 2021

Answer To: For electron affinity of semiconductor materials, please refer to the material parameters table in...

Ishwar answered on Mar 20 2021
143 Votes
Answer: 1 (a)
Answer: 1 (b)
Parallel plate capacitor;
Linear dependence as express by;
Answe
r: 1 (c)
Answer: 1 (d)
Answer: 2 (a)
Barrier energy;
Fermi level of “Au”;
Fermi level of “n-Si”;
Difference between “Au” and “n-Si” Fermi level;
Answer: 2 (b)
Answer: 2 (c)
The fermi level is spatially constant at the position of thermal equilibrium. In case, the p-n junction with the not applied bais, there have the conventional...
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