Bipolar transistor having high emitter efficiency
 A vertical conduction NPN bipolar transistor with a tunneling barrier of silicon carbide in the emitter providing a high emitter injection efficiency and high, stable current gain. The emitter structure comprises a heavily doped polysilicon layer atop a silicon carbide layer that contacts a shallow, heavily doped emitter region at the surface of an epitaxial silicon layer, which is disposed on a monocrystallinie silicon substrate. The silicon carbide layer is about 100 to 200 angstroms thick and has a composition selected to provide an energy band gap in the 1.8 to 3.5 eV range. The thickness and composition of the silicon carbide can be varied within the preferred ranges to tune the transistor's electrical characteristics and simplify the fabrication process. 
STMicroelectronics, Inc.
H H
H01L H01L
inventional additional
Gilles E. Jin Ming Viviane Marguerite
Thomas Liu Fang Do-Bento-Vieira