This invention provides a hetero-junction bipolar transistor (HBT) in which
both a base resistance and a base-collector parasitic capacitance are decreased.
The HBT has a collector (C) 18, a base (B) 20 and an emitter (E)
26. The collector comprises an outer collector region and an inner collector
region, a thickness of the outer collector region is greater than that of the inner
region. The base comprises an intrinsic region and an extrinsic region on the outer
collector region, while the intrinsic base disposed on the inner collector region.
The emitter is disposed on both the intrinsic base and the extrinsic base, and
has a band gap energy greater than that of the base.
