6.012 Microelectronic Devices and Circuits Tutorial #3 Problem 1 – pn junction electrostatics Consider a pn junction with Nd = 5x1017 cm ‐3 and N = 1017 cm ‐3 a as sketched below in Figure T3.1. Figure T3.1: Doping profile for a pn junction a) What is the junction potential drop across the pn junction φJ= φB in thermal equilibrium? b) What is the depletion layer width Xdo in thermal equilibrium? c) What is the electrostatic field at x=0, E(0), in thermal equilibrium? d) What is the electrostatic potential at x= 0, φ()0, in thermal equilibrium ? e) What is the total amount of charge per unit area on the p‐type side of the junction in thermal equilibrium f) What is depletion capacitance, Cj, in thermal equilibrium? g) How do parts a)‐f) change with a reverse bias of VD = ‐3V?MIT OpenCourseWare http://ocw.mit.edu 6.012 Microelectronic Devices and CircuitsSpring 2009 For information about citing these materials or our Terms of Use, visit:
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