Double heterostructure-emitter bipolar transistors (DHEBTs) with emitter edge-thinning design and DHEBTs without that design have been investigated. In the characteristics modeling, a two-dimensional continuity equation and boundary conditions in the base region are employed to determine the various components of base current in a cylindrical mesa-type DHEBT. The influence of structure parameters and emitter edge-thinning design on the current gain of the DHEBT is studied. The effect of quasi-electric field in the base region is taken into account. Switching mechanisms in the DHEBT are also discussed. In the experimental measurement, a DHEBT with an exposed p+ -GaAs base surface exhibits a small offset voltage of 100 mV and a common-emitter current gain of 17. Due to the emitter edge-thinning to suppress the surface recombination current, a DHEBT with an N-AlGaAs passivated surface has a common-emitter current gain of 140 and a negligible offset voltage of 40 mV. With symmetric structures, both devices present bidirectional switching phenomena. Moreover, the emitter edge-thinning design is found having the capability for reducing the holding power in the switching. Possessing both amplifying and switching features, the DHEBTs show good potentials for circuit applications.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry