Fabrication and characterization of advanced ALGaN/GaN high-electron-mobility transistors

Abstract

In this thesis, advanced process technologies, such as in situ surface passivation, strain engineering, and complementary metal-oxide-semiconductor (CMOS) compatible gold-free process, were developed to enhance the electrical characteristics of AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). Chapter 2 reports the development of in situ vacuum anneal and SiH4 or SiH4+NH3 passivation to realize high quality metal gate/high-k dielectric stacks on GaN surface using a multi-chamber metal-organic chemical vapor deposition (MOCVD) gate cluster tool. Chapter 3 demonstrates the realization of AlGaN/GaN MOS-HEMTs with in situ vacuum anneal and SiH4 passivation. Chapter 4 explores the integration of a diamond-like carbon (DLC) stress liner with high intrinsic compressive stress on AlGaN/GaN MOS-HEMTs to further improve device performance. Chapter 5 reports high voltage AlGaN/GaN-on-silicon and on-sapphire MOS-HEMTs using a CMOS compatible gold-free process. AlGaN/GaN-on-sapphire MOS-HEMTs achieved the highest breakdown of 1400 V, as compared to other gold-free AlGaN/GaN HEMTs reported to-date.