UCSB and IQE achieve record-breaking 450 GHz InP HBT
Material for the InP-based DHBT devices was grown by IQE on 3 inch semi-insulating InP wafers by MBE. The epitaxial structures include a graded carbon doped base and superlattice composition grading at the base-collector junction. Devices were fabricated at UCSB using a conventional mesa HBT structure and exhibited ft of 282 GHz and fmax greater than 450 GHz at a current density of 2.3 mA/mm2. This is believed to be the highest fmax ever reported for a mesa HBT. Prior to this work, the highest fmax reported for a DHBT was 300 GHz at a current density of 4.1 mA/mm2.
"The results demonstrate that InP HBTs will continue to see large improvements in speed as dimensions are scaled and epitaxial growth technology is advanced," said UCSB s Mark Rodwell. "IQE has been a tremendous partner in our efforts to develop fast transistors and ICs."
Details of the development may be found in the paper by Dahlström et al.: "Ultra-Wideband DHBTs using a Graded Carbon-Doped InGaAs Base" as presented at the IPRM conference (May 12-16, 2002).
