The Effect of Fluorine Doping in the Charge Trapping Layer on Device Characteristics and Reliability of E-Mode GaN MIS-HEMTs

In this study, we investigate the device characteristics and reliability of the hybrid ferroelectric charge trap gate-stack enhancement-mode gallium nitride MIS-high electron mobility transistors (FEG-HEMTs) with various doping elements in the charge trapping layer (CTL). FEG-HEMTs were fabricated with fluorine-doped (F-HfO <tex-math notation="LaTeX">₂)</tex-math> and nitrogen-doped HfO <tex-math notation="LaTeX">₂</tex-math> (HfON) films as the CTLs. Incorporating fluorine and nitrogen into HfO <tex-math notation="LaTeX">₂</tex-math> resulted in a notable decrease in oxygen vacancy and dangling bond densities. This, in turn, improved the interface stability and subsequently enhanced the device performance and reliability. The F-doped FEG-HEMT was confirmed to have high performance as well as high stability with high threshold voltage ( <tex-math notation="LaTeX">Vₜₕ)</tex-math> of 5.43 V, maximum drain current ( <tex-math notation="LaTeX">I_D, MAX)</tex-math> of 760.2 mA/mm, and breakdown voltage (BV) of 906 V. Furthermore, stress gate BV, retention time, time-dependent dielectric breakdown (TDDB), and constant stress bias test, which contribute significantly to the reliability of FEG gate-stack, are reported in this article.