Heterojunction bipolar transistor, power amplifier including the same, and method for fabricating heterojunction bipolar transistor

摘要

A heterojunction bipolar transistor includes a ballast resistor layer of which resistance increases with an increase in temperature. The ballast resistor layer includes a first ballast resistor sub-layer having a positive temperature coefficient of resistivity in a first temperature range and a second temperature range and a second ballast resistor sub-layer having a negative temperature coefficient of resistivity in the first temperature range and a positive temperature coefficient of resistivity in the second temperature range.