Polycrystalline silicon-germanium emitters for gain control, with application to SiGe HBTs

This paper investigates germanium incorporation into polysilicon emitters for gain control in SiGe heterojunction bipolar transistors. A theory for the base current of a polySiGe emitter is developed, which combines the effects of the polySiGe grains, the grain boundaries and the interfacial layer a...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on electron devices 2003-06, Vol.50 (6), p.1480-1486
Main Authors: Kunz, V.D., de Groot, C.H., Hall, S., Ashburn, P.
Format: Article
Language:English
Subjects:
Charge carrier lifetime
Emitters
Gain
Gain control
Germanium
Germanium alloys
Heterojunction bipolar transistors
Oxides
Semiconductor devices
Semiconductor materials
Silicon
Silicon alloys
Silicon germanides
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This paper investigates germanium incorporation into polysilicon emitters for gain control in SiGe heterojunction bipolar transistors. A theory for the base current of a polySiGe emitter is developed, which combines the effects of the polySiGe grains, the grain boundaries and the interfacial layer at the polySiGe/Si interface into an expression for the effective surface recombination velocity of a polySiGe emitter. Silicon bipolar transistors are fabricated with 0, 10 and 19% Ge in the polySiGe emitter and the variation of base current with Ge content is characterized. The measured base current for a polySiGe emitter increases by a factor of 3.2 for 10% Ge and 4.0 for 19% Ge compared with a control transistor containing no germanium. These values are in good agreement with the theoretical predictions. The competing mechanisms of base current increase by Ge incorporation into the polysilicon and base current decrease due to an interfacial oxide layer are investigated.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2003.813338