Novel C-V measurements based method for the extraction of GaN buffer layer residual doping level in HEMT

This paper presents a new methodology to characterize the GaN buffer doping level which is a critical parameter for epitaxial fabrication of GaN wafers. As demonstrated in this study, its characterization is challenging due to parasitic effects. Capacitance-Voltage (C-V) measurements are carried out on a Metal Insulator Semiconductor (MIS) structure with a gate on Al
₂
O
₃
dielectric using a novel configuration. The experimental study is validated with a self-consistent Poisson-Schrodinger (PS) simulation. Finally, our methodology is applied to a new generation of GaN buffer through a fully and partially (without any contacts) processed wafer, with a Hg-probe C-V measurement performed on the partially processed one.