A bipolar transistor in which the emitter possesses a double "mesa" structure so as to achieve the maximum avoidance of the phenomena of electron/hole recombinations that have a deleterious effect on the current gain. The double mesa emitter can be made out of an alternation of materials M.sub.I /M.sub.II...http://www.google.fr/patents/US5668388?utm_source=gb-gplus-shareBrevet US5668388 - Bipolar transistor with optimized structure
