Improved robustness, stability and linearity in GaN based high electron mobility transistors for 5G applications

Abstract

5G technology requires high frequency and high power transistors. GaN-based high-electron-mobility transistors (HEMTs) are promising candidates to answer these needs. Although it is studied nearly for 30 years, there are still problems with this technology such as high non-linearity, unstable behavior and uncertain-ties in lifetime estimations, to take the lead. Some of the most important problems of GaN HEMT technology are studied elaborately in this thesis. Electro-thermal simulations are used to analyze the heating behavior of HEMT power devices under operation and a new more re-alistic model is developed. Fabrication of devices is governed and highly linear transistors with 6.4 V gate voltage span are achieved by using fin-like structures. 6.5 dB improvement in OIP3 is obtained compared to conventional devices. Fi-nally, the stability and robustness of these devices are studied in the view of passivation. Significant improvement in surface morphology, DC operation, long-term stability, pulsed IV performance, and forward gate bias stress durability has been demonstrated. Findings will help the implementation of GaN HEMT devices into 5G applications.