Fundamental study, characterization, and reliability of vertical GaN FETs

Wide band gap semiconductors have intriguing properties that can be exploited for high-voltage and high-power electronic applications. Some (SiC) have been adopted by the industry and are currently used in high-end products such as electrical vehicles. Others are entering the market as we speak (GaN), yet require further investigations to extend their capabilities and fields of application. One candidate is the vertical GaN field-effect transistor (FET). This device could be of particular interest for very high-voltage applications (1200 V and above).

At imec, we are working toward a full vertical GaN FET for 1200 V applications, yet several challenges need to be addressed. One of those is the robustness and reliability of the device under high-voltage operation. Another objective is to improve the ON-resistance of the device while keeping the OFF-state condition at very high voltages intact.

The main objective of this PhD topic is to gain a deep understanding of the vertical GaN FETs, to help improve the device design and electrical performance, and to characterize the reliability and lifetime of the devices.

The PhD candidate will be involved in all aspects of the making of a high-voltage switch including device design, processing, characterization and data analysis. The primary focus for the PhD student will be on the characterization and data analysis. The student will have to gain a deep understanding of the device physics (eventually with the help of numerical simulations) and help the team in optimizing the device. She or he will have to perform on-wafer electrical measurements and report back to the team. The PhD student joins a team with over a decade of experience in processing, simulation, and characterization of GaN switches in a top-notch environment. The student will receive training by highly-skilled professionals and will be embedded in the GaN device team. Typical tools that will be used by the student include probe stations for on-wafer electrical characterization, software tools for data analysis (python), and TCAD Synopsys software suite.