Effect of emitter contact on current gain of silicon bipolar devices

1 November 1980

journal article
Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices

Vol. 27 (11) , 2051-2055
https://doi.org/10.1109/t-ed.1980.20148

Abstract

The common-emitter current gain β of silicon n-p-n bipolar transistors with shallow (200 nm) emitters contacted by either i) Al, ii) Pd2Si + Al, or iii) n⁺polysilicon + Al are compared. For the same base doping profile, β(Al) is typically about 25 percent larger than β(Pd2Si), while β(poly) is typically several times larger than β(Pd2Si). The dependence of the base current on temperature and on the thickness of the polysilicon layer indicates that the base current is not determined by the silicon-polysilicon interface properties, such as tunneling through an interfacial oxide layer, but by the transport of holes in the n⁺polysilicon layer. A simple two-region (n⁺silicon region and n⁺polysilicon region) model is presented which satisfactorily explains the experimental results in terms of lower hole mobility in the n⁺polysilicon than in the monocrystalline n⁺silicon.

Keywords

This publication has 8 references indexed in Scilit:

The SIS tunnel emitter: A theory for emitters with thin interface layers
IEEE Transactions on Electron Devices, 1979
A polysilicon base bipolar transistor
Published by Institute of Electrical and Electronics Engineers (IEEE) ,1979
Bipolar circuit scaling
Published by Institute of Electrical and Electronics Engineers (IEEE) ,1979
The emitter efficiency of bipolar transistors: Theory and experiments
Solid-State Electronics, 1977
Auger coefficients for highly doped and highly excited silicon
Applied Physics Letters, 1977
High-performance transistors with arsenic-implanted polysil emitters
IEEE Journal of Solid-State Circuits, 1976
Chemical Vapor Deposited Polycrystalline Silicon
Journal of the Electrochemical Society, 1972
Carrier mobilities in silicon empirically related to doping and field
Proceedings of the IEEE, 1967