The influence of polarization Coulomb field scattering on the parasitic source resistance of E-mode P-GaN/AlGaN/GaN heterostructure field-effect transistors

E-mode P-GaN/AlGaN/GaN heterostructure field-effect transistors (HFETs) of various sizes were fabricated, and their parasitic source resistance ( R S ) was measured. The measurement results showed that R S varied greatly with changing gate bias, and the degree of R S change also differed with the gate bias of different-sized device samples. Through theoretical analysis, it is found that polarization Coulomb field (PCF) scattering caused by the device process and gate bias can affect electron mobility ( μ GS ) in the gate-source region, which causes the variations in μ GS for different-sized devices and same-sized devices under different gate biases. When μ GS changes with the device size and gate bias, the R S will change accordingly. Our study is the first to discover the gate bias dependency of R S for E-mode P-GaN/AlGaN/GaN HFETs due to PCF scattering, which provides a new idea for further in-depth studies on the R S of E-mode P-GaN/AlGaN/GaN HFETs and device performance optimization.