L14 March 31 EE5342 – Semiconductor Device Modeling and Characterization Lecture 14 - Spring 2005 Professor Ronald L. Carter

L14 March 32 Y-parameter data 300 mV 700 mV 1000 mV 800 mV 900 mV 500 mV

L14 March 33 Y-parameter data 300 mV 700 mV 1000 mV 800 mV 900 mV 500 mV

L14 March 34 Bipolar junction transistor (BJT) The BJT is a “Si sandwich” Pn  (P=p +,  =p - ) or Np  (N=n +, =n - ) BJT action: npn Forward Active when V BE > 0 and V BC < 0 P n  EBC V EB V CB Charge neutral Region Depletion Region

L14 March 35 BJT coordinate systems 0 z x” c x” 0 WBWB W B +W C -W E 0 xBxB x 0 x’ E x’ Charge neutral Region Depletion Region BaseCollectorEmitter

L14 March 36 BJT boundary and injection cond (npn)

L14 March 37 BJT boundary and injection cond (npn)

L14 March 38 IC npn BJT (* Fig 9.2a)

L14 March 39 npn BJT bands in FA region qV BC qV BE q(V biE -V BE ) q(V biC -V BC ) injection high field

L14 March 310 Coordinate system - prototype npn BJT (Fig 9.8*)

L14 March 311 Notation for npn & pnp BJTs N E, N B, N C E, B, and C doping (maj) x E, x B, x C E, B, and C CNR widths D E, D B, D C D minority for E, B, and C L E, L B, L C L minority for E, B, and C (L 2 min = D min  min )   E0,  B0,  C0 minority carrier life- times for E, B, and C regions

L14 March 312 Notation for npn BJTs only p EO, n BO, p CO : E, B, and C thermal equilibrium minority carrier conc p E (x’), n B (x), p C (x’’): positional mathe- matical function for the E, B, and C total minority carrier concentrations   p E (x’),  n B (x),  p C (x’’): positional ma- thematical function for the excess minority carriers in the E, B, and C

L14 March 313 Notation for pnp BJTs only n EO, p BO, n CO : E, B, and C thermal equilibrium minority carrier conc n E (x’), p B (x), n C (x’’): positional mathe- matical function for the E, B, and C total minority carrier concentrations   n E (x’),  p B (x),  n C (x’’): positional ma- thematical function for the excess minority carriers in the E, B, and C

L14 March 314 npn BJT boundary conditions

L14 March 315 Emitter solution in npn BJT

L14 March 316 Base solution in npn BJT

L14 March 317 Collector solution in npn BJT

L14 March 318 Hyperbolic sine function

L14 March 319 npn BJT regions of operation V BE V BC Forward Active Reverse Active Saturation Cutoff

L14 March 320 npn FA BJT minority carrier distribution (Fig 9.4*)

L14 March 321 npn RA BJT minority carrier distribution (Fig 9.11a*)

L14 March 322 npn cutoff BJT min carrier distribution (Fig 9.10a*)

L14 March 323 npn sat BJT minority carrier distribution (Fig 9.10b*)

L14 March 324 Defining currents in FA mode npn BJT (Fig 9.13*)

L14 March 325 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, * Semiconductor Physics & Devices, by Donald A. Neamen, Irwin, Chicago, 1997.