High gain bipolar transistor
View Patent ↗According to one exemplary embodiment, a bipolar transistor comprises a base having a top surface. The bipolar transistor might be a lateral PNP bipolar transistor and the base may comprise, for example, N type single crystal silicon. The bipolar transistor further comprises an emitter having a top surface, where the emitter is situated on the top surface of the base. The emitter may comprise P+ type single crystal silicon-germanium, for example. The bipolar transistor further comprises an electron barrier layer situated directly on the top surface of the emitter. The electron barrier layer will cause an increase in the gain, or beta, of the bipolar transistor. The electron barrier layer may be a dielectric such as, for example, silicon oxide. In another embodiment, a floating N+ region, instead of the electron barrier layer, is utilized to increase the gain of the bipolar transistor.
1. A bipolar transistor comprising:
a base having a top surface;
an emitter having a top surface, said emitter being situated on said top surface of said base;
an electron barrier layer situated directly on said top surface of said emitter in an opening defined by a plurality of emitter contact layers and said top surface of said emitter, said electron barrier layer causing a base current in said base to decrease;
wherein said emitter separates said electron barrier layer from said base.
2. The bipolar transistor of claim 1 wherein said bipolar transistor is a PNP bipolar transistor.
3. The bipolar transistor of claim 1 wherein said bipolar transistor is a lateral PNP bipolar transistor.
4. The bipolar transistor of claim 1 wherein said electron barrier layer comprises a dielectric.
5. The bipolar transistor of claim 4 wherein said dielectric comprises silicon oxide.
6. The bipolar transistor of claim 1 wherein said electron barrier layer causes an increase in a beta of said bipolar transistor.
7. The bipolar transistor of claim 1 wherein said base comprises N type single crystal silicon.
8. The bipolar transistor of claim 1 wherein said emitter comprises P+ type single crystal silicon-germanium.
9. A PNP bipolar transistor comprising:
a base having a top surface;
an emitter having a top surface, said emitter being situated on said top surface of said base;
a floating N+ region situated directly on said top surface of said emitter in an opening defined by a plurality of emitter contact layers and said top surface of said emitter, said floating N+ region causing a base current in said base to decrease.
10. The PNP bipolar transistor of claim 9 wherein said PNP bipolar transistor is a lateral PNP bipolar transistor.
11. The PNP bipolar transistor of claim 9 wherein said floating N+ region comprises N+ type polysilicon.
12. The PNP bipolar transistor of claim 9 wherein said floating N+ region causes an increase in a beta of said bipolar transistor.
13. The PNP bipolar transistor of claim 9 wherein said base comprises N type single crystal silicon.
14. The PNP bipolar transistor of claim 9 wherein said emitter comprises P+ type single crystal silicon-germanium.
15. The PNP bipolar transistor of claim 9 wherein said floating N+ region comprises a dielectric spacer situated adjacent to said floating N+ region, said dielectric spacer being in contact with said top surface of said emitter.