A novel narrow-base heterojunction bipolar transistor and a multiple-state switching device based on the InP/InGaAlAs material system have been fabricated and demonstrated. Common-emitter current gains up to 28 and 25 are obtained. Due to the use of an InGaAlAs narrow base, interesting topee-shaped current-voltage characteristics presented in the transistor active regime and negative-differential-resistance (NDR) loci are observed under the applied base current of IB = 2 μA/step. In addition, multiple-route and multiple-state S-shaped NDR characteristics are observed at 77 K due to the insertion of the InGaAs quantum well in the base-collector junction. The topee-shaped NDR phenomena are attributed to the modulation of the potential spike at the base-emitter heterojunction. However, the switching behaviours are due to the avalanche multiplication, confinement effect and two-stage barrier lowering effect.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Electrical and Electronic Engineering