Electron velocity overshoot in the collector depletion layer of AlGaAs/GaAs HBT's

1 December 1986

journal article
Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Electron Device Letters

Vol. 7 (12) , 655-657
https://doi.org/10.1109/edl.1986.26509

Abstract

Electron velocity in the collector depletion layer of AlGaAs/ GaAs heterojunction bipolar transistors (HBT's) is characterized by analyzing the cutoff frequencies. The ftvalue of tested HBT's was 40 GHz at a collector voltage VCEof 2 V, and it significantly decreased to 27 GHz at VCE= 5 V. A conventional model assuming a constant electron velocity in the collector depletion region does not account for this ftvariation. A new simple model composed of a velocity overshoot region and a saturation velocity region is proposed and it successfully explains the variation.

Keywords

ELECTRONS
GALLIUM ARSENIDE
CUTOFF FREQUENCY
HETEROJUNCTION BIPOLAR TRANSISTORS
VOLTAGE
TESTING
DOPING
CAPACITANCE MEASUREMENT
TRANSIENT ANALYSIS
INFORMATION ANALYSIS