Study of Drain Access Resistance in Saturation Region of AlGaN/GaN Heterostructure Field-Effect Transistors

A method is proposed to determine drain access resistance in saturation region of AlGaN/GaN heterostructure field-effect transistors (HFETs). The variation of drain access resistance is analyzed qualitatively and quantificationally. Comparing with source access resistance, the difference is attributed to the asymmetry of additional polarization charge distribution at AlGaN/GaN interface. Interaction strength between additional polarization charge and gate–drain channel electron is stronger than that of gate–source channel electron. The drain access resistance components corresponding to polarization Coulomb field (PCF) scattering, polar-optical-phonon (POP) scattering, piezoelectric (PE) scattering, and interface roughness (IFR) scattering are obtained quantificationally. POP scattering dominates drain access resistance with the increase of drain–source current, because of hot-electron and hot-POP effect. Moreover, PCF scattering also plays an important role, especially under low drain–source current, because of stronger PCF scattering potential and lower hot-POP temperature.