Modelling of Multichannel GaN Transistors
The Gallium Nitride High Electron Mobility Transistor (GaN HEMT) is the representative GaN-based wide bandgap semiconductor device. It has been one of the most promising research topics due to its excellent electronic properties in high power, high frequency and high temperature applications. The specific properties of GaN material make the devices have a wide range of potential applications. This thesis discusses the fundamental physical models used in TCAD sentaurus simulations, a widely used tool for simulating and analysing the behaviours and characteristics of semiconductor devices. However, simulating wide bandgap-based devices presents specific challenges that necessitate careful model selection. This work also includes a discussion of the specific modelling considerations for GaN HEMTs within TCAD. Furthermore, for a single channel p-GaN gate HEMT, this thesis compares the gate Schottky contact and ohmic contact, evaluating their reliability and the influence of the field plate on device performance. Further research extends to multichannel HEMTs, establishing a multichannel simulation platform to investigate the complexities of channel control and carrier generation within GaN-based doped multichannel superjunction (SJ) structures. The simulations reveal sequential depletion in doped structures and simultaneous depletion in undoped structures. Results from this model demonstrate that increasing the number of channels in multichannel structures does not necessarily improve the figure-of-merit (FOM). Building on the previous study, this thesis explores novel multichannel structures, including p-GaN bulk with an AlGaN dielectric layer (MPAl-trigate) and metal-oxide-p-GaN tri-gate (MOP-trigate). These designs enable normally-off operation without reducing the gate fin width. Research in this area is ongoing to further refine and explore the characteristics.
GaN, HEMT, p-GaN, Multichannel, Tri-gate
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