Several design principles based on compositional grading and heavy doping of the base region of a heterojunction bipolar transistor (HBT) have been presented. Physical and technological advantages underlying composition induced design criteria of InP/GaxIn1-xAs HBTs have been discussed. A number of issues such as superlattice based grading in the base region, base resistance vs base region grading, the emitter-base junction design, tradeoffs between base region grading and the nonuniform doping of the base region, and the surface recombination at the external base region, have been articulated. (C) 2002 Elsevier Science Ltd. All rights reserved.