Effect of emitter contact on current gain of silicon bipolar devices
Abstract
The common-emitter current gain beta of silicon n-p-n bipolar transistors with shallow (200 nm) emitters contacted by (1) Al, (2) Pd2Si + Al, or (3) n(+) polysilicon + Al are compared. For the same base doping profile, beta(Al) is typically about 25% larger than beta(Pd2Si), while beta(poly) is typically several times larger than beta(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.
- Publication:
-
IEEE Transactions on Electron Devices
- Pub Date:
- November 1980
- DOI:
- 10.1109/T-ED.1980.20148
- Bibcode:
- 1980ITED...27.2051N
- Keywords:
-
- Bipolar Transistors;
- Electric Contacts;
- Emitters;
- Silicon Transistors;
- Volt-Ampere Characteristics;
- Amplification;
- Design Analysis;
- Electronic Equipment;
- Electronics and Electrical Engineering