Effects of base-emitter junction on the resonant tunneling bipolar transistor with double barriers in teh emitter

A resonant-tunneling bipolar transistor with a series of double barriers (DBs) in the emitter grown by molecular beam epitaxy was studied. The current-voltage characteristics exhibiting S-shaped negative differential resistance (NDR) but not N-shaped NDR behavior were observed. Due to the influence of the base-emitter junction which cannot reach a flatband condition at the resonant situation, the subband level of the DB is smaller than the electrostatic potential of the base-emitter (B-E) junction. Thus the N-type NDR cannot be observed. With further increasing bias, avalanche breakdown occurs in the base-collector (B-C) junction to produce electron-hole pairs. Multiple S-shaped NDR behavior is observed in the collector current-voltage (I_C-V_CE) characteristics from holes sequentially accumulated at the valence band maxima of teh base region and a series of DB heterostructures in the emitter. Transistor behavior is observed for high-level base injection (e.g. 1 mA/step) while the switching characteristics of a thyristor are observed for low-level base injection (e.g. 50 μA/step). The multistate operation of the new phenomenon opens up opportunities for digital and analog circuits with greatly reduced complexity and multiple valued logic.