1. 4.1, text

2. 4.2, text

3. 4.5, text

4. 5.1, text.

5. 5.2, text.

6. A silicon step junction N_A = 4X10¹⁸/cm³ (assume non-degenerate), ND = 10¹⁶/cm³, is at 300K. Calculate the following in equilibrium, assuming the depletion approximation.
a. V_bi
b. x_n, x_p, and W
c. n_po and p_no
d. Percentage of the depletion region on the p-side

7. For the diode in the previous problem:
a. Determine the junction capacitance for an applied voltage of 0 V.
b. Determine the saturation current, assuming t_n = t_p = 10^-6 sec.

c. Recompute a. and b. for a change in N_A to 4X10¹⁷.
d. Recompute a. and b. for a change in ND to 10¹⁵, keeping N_A at 4X10¹⁸.
e. Which change has a larger effect on the characteristics?

8. An attempt to measure the internal contact potential of a p-n junction is made by connecting a voltmeter with copper leads to contacts on opposite sides of the junction. The voltmeter reads zero. Explain the failure of this method.

9. Derive the I-V characteristics of the short-base diode shown, where the boundary condition at the contact on the n-side is given by Sp very large (equivalent to saying that the excess minority carrier concentration is zero). Note that this is not in either limit discussed in the text! You need to do the diffusion problem including both positive and negative exponentials.

xn' - xn is on the order of Lp, xp' - xp >> Ln.

Lp and Ln are the minority carrier diffusion lengths.