Applications of an In0.53Ga0.25Al0.22As/InP continuous-conduction-band structure for ultralow current operation transistors

Abstract

Based on the compositional dependence on the conduction band discontinuity, a significant heterojunction bipolar transistor (HBT) with a continuous conduction band heterointerface between the InP emitter and the In0.53Ga0.25Al0.22As base is fabricated. Experimentally, due to the elimination of the potential spike, a very low offset voltage of 50 mV is observed. Also, the studied device exhibits better breakdown characteristics and lower output conductance as compared with other InP/InGaAs or AlInAs/InGaAs HBTs. Furthermore, attributed to the enhancement of the hole confinement by an inserted δ-doped sheet at the emitter–base interface, a dramatic current gain about 4 is found even under an ultralow current operation regime (IC⩽5 nA).

The influence of a -doped sheet on DC performances of InP/InGaAs heterojunction bipolar transistors

“…However, the quaternary In 1−x−y Ga x Al y As alloy must be precisely controlled to meet the requirement of a high-quality epitaxial layer [10]. In addition, δ-doped AlGaAs/GaAs and InGaP/GaAs HBT's have been well demonstrated to overcome the above disadvantage and still maintain large current gain [10][11][12]. The use of a δ-doped sheet can lower the barrier on the emitter side and eliminate the potential spike.…”

“…Recently, the In 0.53 Ga 0.25 Al 0.22 As/InP heterostructure with a nearly continuous conduction band has been proposed for improving the offset voltage. However, the quaternary In 1−x−y Ga x Al y As alloy must be precisely controlled to meet the requirement of a high-quality epitaxial layer [10]. In addition, δ-doped AlGaAs/GaAs and InGaP/GaAs HBT's have been well demonstrated to overcome the above disadvantage and still maintain large current gain [10][11][12].…”