Realization of GaN-based technology for high power and high frequency applications

Abstract

Summary form only given. Wide band gap semiconductor of GaN and its related materials are promising for future power and high frequency applications. In particular, the GaN high electron mobility transistor (HEMT) grown on large-size Si substrate is suitable for low-lost and high power switching applications. The GaN HEMT could be fabricated into convertors and invertors for electrified vehicle (EV). In order to achieve GaN HEMT device with high efficiency, various issues have to be considered. These include the careful design of material structure and device layout. Furthermore, surface passivation techniques are critical for reducing dynamic on-resistance (Ron) and improving reliability. For safety purpose, a normally-off device is required. Thus, the pros and cons of normally-off device fabrication approaches such as gate-recessed, p-GaN cap and F-plasma treatment will be discussed. The possibility of using fully-copper-based metallization will also be addressed. The copper metallization can reduce the fabrication cost effectively by replacing the conventional gold metallization. Finally, power module is demonstrated by employing the GaN HEMTs and Schottky barrier diodes. For future RF power application, GaN HEMTs on SiC substrate are fabricated. The GaN material grown on SiC can achieve better crystal quality and the HEMT devices are also beneficial from better thermal dissipation due to high thermal conductivity SiC substrate. GaN HEMT on SiC could be used in future high frequency applications such as formilitary phased array radar and civilian 4th-generation base station. Besides the AlGaN/GaN HEMT structure, new material structures such as InAlN/GaN and AlN/GaN are also demonstrated. These structures have great potential for very high frequency (>300 GHz) and high power applications.