Abstract
In recent years, the wireless technology has been used widely for different applications such as mobile phones, wireless charging, and automotive sensors. This leads to an exponential increased demand of high frequency and high power transistors. GaN-based devices, owing to the superior material properties, have attracted significant attentions and become a popular research topic over the past decade. The AlGaN/GaN high electron mobility transistors (HEMTs) with an excellent mobility and high saturation velocity under a high electric field are suitable for millimeter wave applications. More recently, these devices fabricated on the silicon substrate with lower cost and possibility to integrate with CMOS devices showed significant progress in device characteristics. However, the transistor reliability is still an issue. This thesis focuses on design and analysis of the high-frequency device of InAlN /GaN HEMTs on the Si substrates. The lattice-matched InAlN/GaN interface is expected to improve the device reliability issue. The high carrier density in the 2DEG channel can also enhance the transistor frequency response. The fabricated devices show a best f_T and f_max up to 50 GHz and 101 GHz respectively with a gate-recess structure. The devices with Schottky drain/source extension also result in improved high frequency performance. We analyze the devices in details by using the small-signal equivalent circuit model. Based on the analysis of the equivalent circuit model parameters, the dominant parasitic effects to limit the device RF characteristics have been identified. The obtained results can be used to understand how to further improve the device performance regarding the device fabrication and the epitaxy structure of the InAlN/GaN on the Si substrate.