Homework #9 - due Thursday, 4 May 2006, in class

1.  Problem 6.9 in chapter 6 of Muller & Kamins, p. 322 in 3rd edition. Hint: the result of problem 1 is that the field is E = kT/qL for doping N = No exp(-x/L).

2.  Problem 6.14 (a) in chapter 6 of Muller & Kamins, p.322 in 3rd edition. Hint: use a simplified Ebers Moll model in which a current generator qG is in parallel with the current generator: (alphaF*IF).

3.  The emitter and collector regions of a Si alloyed p-n-p transistor are heavily doped, and the impurity concentration in the base is 1E15cm-3. Calculate the base-width that will make the avalanche breakdown voltage equal to the punch-through voltage. The punch through voltage is given by: Vpt = q Nd Wbo^2/(2es) , where Wbo is the metallurgical base width. Assume that avalanche breakdown occurs when the maximum field strength in the C-B depletion region becomes 5 x 10^5V/cm.

4.  Consider a pnp bipolar transistor biased so that the emitter is shorted to the base, and the base collector is reverse biased with voltage VBC. Use the Ebers Moll model with deltaPE and deltaPC to find the currents IE, IC, and IB in terms of standard parameters: IES, ICS, alphaN and alphaI. Sketch the hole concentration in the base and indicate values for pn(0) and pn(Wb).
 

5.  Problem 7.1 in chapter 7 of Muller & Kamins, p. 375 in 3rd edition. Hint: for an npn transistor, use Eqns 7.1.1 with constant base doping, and 7.1.3, and 7.1.4.
 

  Homework assignments will appear on the web at: http://www.ece.udel.edu/~kolodzey/courses/eleg646s06.html
  Note: On each homework and report submission, please give your name, the due date, assignment number and the course number. For full credit - include units/dimensions for all numerical quantities