Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/ Semiconductor Device Modeling and Characterization – EE5342 Lecture 19 – Spring 2011 Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/

IC npn BJT (*Fig 9.2a) ©rlc L19-23Mar2011

npn BJT bands in FA region q(VbiE-VBE ) q(VbiC-VBC ) qVBE qVBC injection high field ©rlc L19-23Mar2011

Coordinate system - prototype npn BJT (Fig 9.8*) ©rlc L19-23Mar2011

Notation for npn & pnp BJTs NE, NB, NC E, B, and C doping (maj) xE, xB, xC E, B, and C CNR widths DE, DB, DC Dminority for E, B, and C LE, LB, LC Lminority for E, B, and C (L2min = Dmin tmin) The minority carrier lifetimes in the E, B, and C regions are tE0, tB0, & tC0 ©rlc L19-23Mar2011

Notation for npn BJTs only pEO, nBO, pCO: E, B, and C thermal equilibrium minority carrier conc pE(x’), nB(x), pC(x’’): positional mathe- matical function for the E, B, and C total minority carrier concentrations The excess carrier concentrations dpE(x’), dnB(x), dpC(x’’) are the positional mathematical functions in the E, B, and C ©rlc L19-23Mar2011

Notation for pnp BJTs only nEO, pBO, nCO: E, B, and C thermal equilibrium minority carrier conc nE(x’), pB(x), nC (x’’): positional mathe- matical function for the E, B, and C total minority carrier concentrations dnE(x’), dpB(x), dnC(x’’): positional ma- thematical function for the excess minority carriers in the E, B, and C ©rlc L19-23Mar2011

npn BJT boundary conditions ©rlc L19-23Mar2011

Emitter solution in npn BJT ©rlc L19-23Mar2011

Base solution in npn BJT ©rlc L19-23Mar2011

Collector solution in npn BJT ©rlc L19-23Mar2011

Hyperbolic sine function ©rlc L19-23Mar2011

npn BJT regions of operation VBC Reverse Active Saturation VBE Forward Active Cutoff ©rlc L19-23Mar2011

npn FA BJT minority carrier distribution (Fig 9.4*) ©rlc L19-23Mar2011

npn RA BJT minority carrier distribution (Fig 9.11a*) ©rlc L19-23Mar2011

npn cutoff BJT min carrier distribution (Fig 9.10a*) ©rlc L19-23Mar2011

npn sat BJT minority carrier distribution (Fig 9.10b*) ©rlc L19-23Mar2011

Defining currents in FA mode npn BJT (Fig 9.13*) ©rlc L19-23Mar2011

npn BJT currents (F A region, ©RLC) IC = JCAC IB=-(IE+IC ) JnE JnC IE = -JEAE JRB=JnE-JnC JpE JGC JRE JpC ©rlc L19-23Mar2011

Common base current gain, aF (cont.) ©rlc L19-23Mar2011

References 1 OrCAD PSpice A/D Manual, Version 9.1, November, 1999, OrCAD, Inc. 2 Semiconductor Device Modeling with SPICE, 2nd ed., by Massobrio and Antognetti, McGraw Hill, NY, 1993. * Semiconductor Physics & Devices, by Donald A. Neamen, Irwin, Chicago, 1997. ©rlc L19-23Mar2011