Optimization of the field-plate geometryfor GaN-based HEMTs
Project Description
In this semester project a Gallium Nitride (GaN) based High-Electron Mobility Transistor (HEMT) will be optimized for high breakdown voltages: three basic field-plate geometries are simulated and compared to experimental results. Finally, based on the experimentally verified model, a new,optimized field-plate design will be proposed by the student.
A field-plate is used to reshape the electrical field distribution and reduces its peak value at the drain-side of the gate: This minimizes the risk of a break-down at the drain side and hinders high field trapping of electrons. A well designed field plate maximizes the off-state breakdown voltage BVoff without considerable decrease in the current gain cutoff frequency fT. For GaN based HEMT transistors the product fT BVoff is roughly 5 THzV. Here, we are aiming for BVoff > 100V (i.e. fT is around 50 GHz).