©rlc L16-07Mar20111 PiN Diode PiN: N a >> N int (= N - ) & N int << N d W i = Intrinsic region (metall.) width E m,P-T = Peak field mag. when x n = W i V bi = i = V t ln(N a N d /n i 2 ) V bi,int = i,int = V t ln(N a N int /n i 2 ) V HL = V t ln(N d /N int ), the offset at N + N - V bi = V bi,int + V HL V PT = applied voltage when x n = W i

©rlc L16-07Mar20112 PiN Diode Depletion Fields Normalized Position, x = x/Wi Normalized Field, E/E m,P-T x p x n xnxn -x p

©rlc L16-07Mar20113 PiN Diode Depletion Conditions

©rlc L16-07Mar20114 CV data and N(x) calculation

©rlc L16-07Mar20115 Diode Switching Consider the charging and discharging of a Pn diode –(N a > N d ) –W d << Lp –For t < 0, apply the Thevenin pair V F and R F, so that in steady state I F = (V F - V a )/R F, V F >> V a, so current source –For t > 0, apply V R and R R I R = (V R + V a )/R R, V R >> V a, so current source

©rlc L16-07Mar20116 Diode switching (cont.) + + VFVF VRVR D R RFRF Sw R: t > 0 F: t < 0 V F,V R >> V a

©rlc L16-07Mar20117 Diode charge for t < 0 xnxn x nc x pnpn p no

©rlc L16-07Mar20118 Diode charge for t >>> 0 (long times) xnxn x nc x pnpn p no

©rlc L16-07Mar20119 Equation summary

©rlc L16-07Mar Snapshot for t barely > 0 xnxn x nc x pnpn p no Total charge removed, Q dis =I R t

©rlc L16-07Mar I(t) for diode switching IDID t IFIF -I R tsts t s +t rr I R

©rlc L16-07Mar References 1 Semiconductor Device Modeling with SPICE, 2nd ed., by Massobrio and Antognetti, McGraw Hill, NY, **OrCAD Pspice A/D Reference Guide, Copyright 1999, OrCAD, Inc. ***MicroSim OnLine Manual, MicroSim Corporation, 1996.