Patent ID: 7795103

Claim:
A method for creating a depleted emitter of a bipolar transistor, comprising: forming a base layer of said bipolar transistor with a first dopant of one polarity, wherein said base layer is eventually connected to a base terminal; forming an emitter layer of said bipolar transistor with a second dopant above said base layer to create an emitter-base junction, wherein said second dopant having an opposite polarity to said first dopant; forming a thin termination layer of heavy doping of said second dopant on top of said emitter layer by a thermal process, wherein said thermal process allows said dopant of the termination layer to stay within said emitter layer, such that said emitter-base junction does not become a normal n + -p or p + -n junction and the built-in potential of said emitter-base junction ranges from about 0.9 eV to about 0.4 eV; and forming a metallization layer above said termination layer, wherein said termination layer can provide an ohmic contact to said metallization layer.