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 (mu(GS)) in the gate-source region, which causes the variations in mu(GS) for different-sized devices and same-sized devices under different gate biases. When mu(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.