ELE533 Bipolar Devices

Mid Term Exam
October 25, 2005

Name_____________________________________

1. Consider a silicon pn junction. The p side is uniformly doped with 5x10¹⁸ acceptors/cm³. The n side is doped with 2x10¹⁶ donors/cm³.
   The contact on the p-side is 2 microns from the junction. The contact on the n-side is 10 microns from the junction. The junction area is 10 microns by 10 microns.
   1. What is the built in potential?

   2. What is the position of the Fermi level relative to the intrinsic level on the n side of the junction?

   3. What is the value of the saturation current, Is, in the equation,

      I = Is*e^V/Vt

   4. Draw the equilibrium energy band diagram for this junction, including numerical values for the Fermi level position relative to the intrinsic level on each side. Show the built-in potential on the diagram.