Full-band simulations of InP/GaAsSb/InP Double Heterojunction Bipolar Transistors (DHBTs)
The Laboratory for Millimeter Wave Electronics (MWE) of the ETHZ is developing and fabricating InP/GaAsSb/InP DHBTs for application in modern lightwave communication systems. The conduction band edge of the GaAsSb base sits above the conduction band edge of the InP collector, thus realizing an injection ramp for electrons reaching the base/collector junction and improving the transistor delay. However, recent studies have shown that electrons situated in the L-valley of the GaAsSb layer cannot be efficiently transferred to the L-valley of InP because the latter is situated at higher energies (see illustration on the left). Such electrons are reflected back towards the emitter side. The reason for this behavior is "momentum conservation": without any external interaction, an electron cannot escape the valley it belongs to. The goal of this project is to investigate with a full-band and atomistic simulator what happens if the GaAsSb/InP junction contains atomic roughness. In this case, momentum conservation is broken and L-valley electrons might eventually transfer from the L-valley of GaAsSb to the Gamma-valley of InP.
- Looking for 1 Semester/Master student
- Contact: Mathieu Luisier
- Interest in device modeling
- 20% Theory
- 20% Model Implementation
- 60% Simulations