Bipolar transistor having collector with grading

摘要

This disclosure relates to bipolar transistors, such as heterojunction bipolar transistors, having at least one grading in the collector. One aspect of this disclosure is a bipolar transistor that includes a collector having a high doping concentration at a junction with the base and at least one grading in which doping concentration increases away from the base. In some embodiments, the high doping concentration can be at least about 3×1016 cm−3. According to certain embodiments, the collector includes two gradings. Such bipolar transistors can be implemented, for example, in power amplifiers.

主权项

1. A bipolar transistor comprising a collector, a base disposed over the collector, and an emitter, the collector having a substantially flat doping concentration of at least 5×1016 cm−3 in a first collector region abutting the base such that an amplifier that includes the bipolar transistor has an alternative channel power ratio (ACPR2) of no greater than about −65 dBc, the collector also having an other collector region under the first collector region, the other collector region including at least one continuous grading having a minimum doping concentration of about one order of magnitude less than the doping concentrating of the first collector region, and the doping concentration of the at least one continuous grading increasing away from the first collector region.