MODELLING, SIMULATION, FABRICATION AND CHARACTERISATION OF ALGAN/GAN FIN-GATE HIGH ELECTION MOBILITY TRANSISTERS (FIN-HEMTS)

Abstract

Aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) have emerged as promising candidates for high-power and high-frequency operations. Recently the fin-gate structure has been reported as an effective approach to obtain normally-off HEMTs. In this thesis, modelling, simulation, fabrication, and characterisation of the fin-gate HEMTs are carried out thoroughly. Firstly, physical models on threshold voltage and saturation current of fin-gate MIS-HEMTs have been established and verified. Subsequently, fin-gate MIS-HEMTs towards improved electrical performances are designed, fabricated, and characterised. The static I-V characterisations indicate that fin-gate structure is applicable for positive shifting of threshold voltage, reduced on-state resistance, increased saturation current, reduced off-state leakage current, and improved high temperature stability. Thirdly, transient switching performances are characterised for planar and fin-gate HEMTs. The physical mechanisms on the suppressed dynamic on-state resistance degradation by the fin-gate structure are investigated. Finally, the integration of GaN-based HEMTs and LEDs is designed and simulated, as an application of HEMTs.