[40 points] PROBLEM # 1 A pn junction has the doping profile sketched below. Throughout the problem assume the carrier concentrations may be neglected (n=0, p=0) in the 0 ≤ x ≤ xi region of the diode. a. What is the built-in voltage across the junction? Justify your answer b. Invoking the depletion approximation, make a sketch of the charge density inside the diode versus x. c. Obtain an analytical solution for the electric field, E(x) at all points inside the depletion regions (-xp ≤ x ≤ xn). Show all steps and also make a sketch of E(x). Midterm 2, ECE 448- Spring 2022, UIC Name: Page 2 of 4 d. Draw the energy band diagram for the diode under equilibrium conditions. Clearly indicate x = 0 and x= xi points on your diagram.
[10 points] PROBLEM # 2 Establish a small-signal equivalent model for the common base configuration. Provide a summary of all the device parameters. Midterm 2, ECE 448- Spring 2022, UIC Name: Page 3 of 4
[30 points] PROBLEM # 3 Given a npn BJT where IEn = 100 μA, IEp = 1 μA, ICn = 99 μA, and ICp = 0.1 μA, calculate: a. αT b. γ c. IE, IC, IB d. αdc e. βdc f. ICB0 and ICE0 Midterm 2, ECE 448- Spring 2022, UIC Name: Page 4 of 4
[20 points] PROBLEM # 4 a. What is base-width modulation in a bipolar junction device? How can we reduce the effects of base width modulation?