EC310 - Fall 2021 HW(4):PN Forward biasing Due to 1/Jan/2022 Q1) Consider a P N junction diode with No = 10 cm in the N region, Tp is given to be 1 usec. a) Determine the diffusion length L on the N-type side. b) What are the excess hole density and excess electron density at the depletion-layer edge on the N-type side under (a) equilibrium and (b) forward bias V = 0.4 V? Q2) A one-sided P'N Si junction at 300K is doped with N1 = 10cm. Design the junction so that the capacitance per unit area C;=0.85 nF at Vr=4.0 V. Q3) Consider a Si p-n junction with n-type doping concentration of 106 cm and is forward biased with V=0.8 V at 300 K. Calculate the minority-carrier hole concentration at the edge of the space charge region. Q4) An ideal silicon p-n junction has No = 10 cm", N, = 10cm, 1,-1,-10s, D. = 21 cm/s, D, = 10 cm/s and a device area of 1.2 x 10 cm (a) Calculate the theoretical saturation current at 300 K. (b) Calculate the forward and reverse currents at +0.7 V. Extra problem Q5) *Consider an ideal, silicon PN junction diode with uniform cross section and constant doping on both sides of the junction. The diode is made from 10.cm P-type and 0.2 0.cm N-type materials in which the recombination lifetimes are ta = 10-6S and tp = 10-s, respectively. a) What is the value of the built-in voltage? b) Calculate the density of the minority carriers at the edge of the depletion layer when the applied voltage is 0.589 V(which is 23 * KT/C). c) Sketch the majority and minority carrier current as functions of distance from the junction on both sides of the junction, under the bias voltage of part (b)