High-performance P-n-p AlGaAs/GaAs heterojunction bipolar transistors - A theoretical analysis

A simple analysis is used to show that an AlGaAs/GaAs P-n-p heterojunction bipolar transistor (HBT) incorporating a thin graded-composition Al(x)Ga(1-x)As base can yield high-frequency performance comparable to the N-p-n structure for millimeter wave and digital applications. The f(tau) and f(max) of the P-n-p device are 1/2-2/3 and equal, respectively, to these parameters for the N-p-n device, which conceptually opens the possibility of new N-p-n/P-n-p complementary HBT circuits. The specific values of f(tau) and f(max) presented here also suggest that f(max) for both types of devices should eventually exceed 100 GHz by a substantial margin through the use of submicrometer, self-aligned structures.