Bipolar transistor with a base layer having an extremely low resistance and method for fabricating the same

摘要

A base region structure involved in a bipolar transistor, wherein the base region comprises a compound semiconductor epitaxial layer (7) formed in a recessed portion (5) provided by etching in an upper region of a semiconductor substrate (1) and the recessed portion (5) has a depth corresponding to a thickness of the compound semiconductor epitaxial layer (7) so that the base region has a top surface positioned at the same level as a top surface of the semiconductor substrate (1).