The thesis discusses the status of research regarding HBTs, including a review
of state-of-the-art devices, a review of state-of-the-art device simulators,
with emphasis on MINIMOS-NT, and a discussion on the materials and material
systems on which HBTs are based on. MINIMOS-NT is a generic two-dimensional
device/circuit simulator used in the VISTA TCAD framework. A large part of the
work presented in this thesis is on the development and the practical
application of MINIMOS-NT. A detailed discussion on the physical modeling in
MINIMOS-NT is presented. It contains models for the lattice, thermal, and
transport properties of various semiconductor materials, as well as models for
several important effects taking place in HBTs. Critical issues concerning
simulation of heterostructures are analyzed, such as interface modeling at
heterojunctions and insulator surfaces, band structure and bandgap narrowing,
the modeling of self-heating and high-field effects.
Simulation results for several different types of GaAs-based and Si-based HBTs demonstrating the extended capabilities of MINIMOS-NT are shown, most of them in comparison with experimental data. Special emphasis is put on the simulation of high-power AlGaAs/GaAs and InGaP/GaAs HBTs. Two-dimensional DC-simulations of different types of one-finger devices in very good agreement with measured data in a wide temperature range are demonstrated. Self-heating effects are accounted for the output device characteristics. The work is extended with transient simulation of small signal parameters to connect DC- and RF- device operation. A comparison of simulated and measured S-parameters and the dependence of on some device parameters are presented. Device reliability investigations which confirm the usefulness of device simulation for practical applications are also offered. Examples of SiGe HBTs and polysilicon emitter BJT conclude the work presented in the thesis.