ABSTRACT
This chapter describes the charge trapping mechanisms that limit the dynamic performance of gallium nitride (GaN)-high electron mobility transistors (HEMTs). It discusses the different methods that are commonly used for the extraction of the properties of the defects responsible for current collapse: capacitance deep-level transient spectroscopy, deep-level optical spectroscopy, dynamic transconductance measurements, and drain current transient measurements. The chapter examines the properties of the defects that are most commonly observed in GaN-based materials and devices. It deals with the degradation mechanisms that limit the lifetime of state-of-the-art HEMTs: transistor based on GaN may degrade due to several mechanisms. The chapter sets out that the improvement of the performance and of the reliability of GaN-based transistors requires an integrated approach; the growth and processing conditions must be optimized with the aim of reaching high frequency/power operation, and high breakdown voltages.
