In this paper, we will investigate three GaAs-based heterostructure-emitter bipolar transistors (HEBTs). These HEBTs have different heterostructure-confinement material systems, e.g., Al0.5Ga0.5As/GaAs, In0.49Ga0.51P/GaAs, and Al0.45Ga0.55As/In0.2Ga0.8As/GaAs. For the studied devices, an n-GaAs emitter layer inserted between the confinement and base layer is expected to eliminate the potential spike at emitter-base (E-B) junction. Therefore, the low collector-emitter offset voltage (ΔVCE) is obtained. For the AlGaAs/GaAs HEBT, experimental results show that a current gain of 180 and a low offset voltage of 80 mV are acquired. In addition, for the InGaP/GaAs HEBT, the current gain is only 60 attributed to the use of larger emitter layer thickness (700 Å) which causes a large recombination current in neutral-emitter regime even when a large valence band discontinuity to conduction band discontinuity ratio (ΔEv/ΔEc) is presented. On the other hand, for the AlGaAs/InGaAs/GaAs HEBT, the ΔEv value can be enhanced due to the insertion of InGaAs quantum well (QW) between the n-GaAs emitter and the P+-GaAs base layer. Thus, the confinement effect of minority carriers is enhanced and a current gain of 280 is obtained, simultaneously. Consequently, our studied devices will provide a good promise for the transistor design and circuit applications.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry