Title :
Extraction of the average collector velocity in high-speed "Type-II" InP-GaAsSb-InP DHBTs
Author :
Liu, H.G. ; Tao, N. ; Watkins, S.P. ; Bolognesi, C.R.
Author_Institution :
Dept. of Phys., Simon Fraser Univ., Burnaby, BC, Canada
Abstract :
In "type-II" NpN InP-GaAsSb-InP double heterostructure bipolar transistors DHBTs), the p+ GaAsSb base conduction band edge lies ΔEC above the InP collector conduction band: a small ballistic injection energy ΔEC is thus imparted to electrons as they are launched into the collector. The resulting high initial velocity should in principle reduce the collector signal delay time in comparison to the case where thermal electrons are accelerated by the collector electric field alone. We extract the bias dependence of the average collector electron velocity in high-speed InP-GaAs0.62Sb0.38-InP DHBTs, and find a maximum average velocity reaching 4×107 cm/s across a 2000 Å InP collector. This finding provides evidence of the performance advantage afforded by abrupt type-II base/collector (B/C) junctions for collector transport when compared to other B/C junctions.
Keywords :
III-V semiconductors; ballistic transport; conduction bands; gallium arsenide; gallium compounds; heterojunction bipolar transistors; indium compounds; InP collector conduction band; InP-GaAs0.62Sb0.38-InP; average collector velocity; ballistic injection energy; bias dependence; collector electric field; collector signal delay time; collector transport; conduction band edge; double heterostructure bipolar transistors; electron velocity; high-speed DHBT; thermal electrons; type-II DHBT; type-II base/collector junctions; Acceleration; Bipolar transistors; Delay effects; Double heterojunction bipolar transistors; Electrons; Fabrication; Helium; Heterojunction bipolar transistors; Indium phosphide; Wet etching; 65; GaAsSb; HBTs; heterojunction bipolar transistors; indium phosphide;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2004.838553
