On the multiple negative-differential-resistance (MNDR) InGap/GaAs resonant tunneling bipolar transistors

Two InGaP/GaAs resonant tunneling bipolar transistors (RTBTs) with different superlattice (SL) structures in the emitters are fabricated and studied. The uniform and modulated widths of barriers are respectively utilized in the specific SL structures. Based on the calculations, the ground state and first excited state minibands are estimated from the transmission probability. The electron transport of RT through SL structures is significantly determined by the electric field behaviors across the barriers. Experimentally, the excellent transistor characteristics including the small saturation voltage, small offset voltage, high breakdown voltages are obtained due to the insertion of δ-doping sheet at the base-collector (B-C) heterointerface. Furthermore, at higher current regimes, the double-and quaternary-negative difference resistance (NDR) phenomena are observed in agreement with the theoretical prediction at 300 K.