Multiple quantized switching behaviours (MQSB) of functional heterostructure-emitter bipolar transistors (HEBTs) with multiple carrier confinement heterostructures

In this paper we will demonstrate the interesting multiple quantized switching behaviours (MQSB), or the multiple negative differential resistance (MNDR) phenomena, resulting from the avalanche multiplication process and multiple carrier confinement effect of functional heterostructure-emitter bipolar transistors (HEBTs) under inverted operation mode. As the applied emitter-collector (E-C) bias V_EC is high enough, electron-hole pairs would be generated by avalanche multiplication near the reverse biased emitter-base (E-B) junction. This leads to the sequential carrier confinement process and successively suppresses the potential barrier height. Thus, the MQSB or MNDR are observed. For the AlGaAs/GaAs HEBT, because hole and electron accumulation may occur simultaneously, only a single S-shaped NDR is obtained due to the potential barrier lowering effect. However, for the InGaP/GaAs HEBT and AGaAs/InGaAs/GaAs HEHBT interesting MNDR phenomena are obtained due to the distinct two-stage barrier lowering mechanisms. These effects are caused by the large ratio of valence band discontinuity to conduction band discontinuity (ΔE_v/ΔE_c) at InGaP/GaAs heterointerface and the insertion of an InGaAs quantum well (QW) at the base regime respectively.