Silicon germanium emitter

Details Silicon germanium emitter Silicon germanium emitter

2007-11-13

2007-11-13

Jackson, Jerome (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Heterojunction device

Bipolar transistor

C257S197000, C438S235000, C438S309000, C438S312000

Reexamination Certificate

active

11308541

ABSTRACT:
Disclosed are an improved hetero-junction bipolar transistor (HBT) structure and a method of forming the structure that incorporates a silicon-germanium emitter layer with a graded germanium profile. The graded germanium concentration creates a quasi-drift field in the neutral region of the emitter layer. This quasi-drift field induces valence bandgap grading within the emitter layer so as to accelerate movement of holes from the base layer through the emitter layer. Accelerated movement of the holes from the base layer through the emitter layer reduces emitter delay time and thereby, increases the cut-off frequency (fT) and the maximum oscillation frequency (fMAX) of the resultant HBT.

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Cressler et al., “Silicon Germanium Heterojunction Bipolar Transistors,” Artech House, Boston, MA, Dec. 2003, p. 170.

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