Study of Gate Width Influence on Extrinsic Transconductance in AlGaN/GaN Heterostructure Field-Effect Transistors With Polarization Coulomb Field Scattering

Abstract

AlGaN/GaN heterostructure FETs with the same gate length and different gate widths were fabricated, and the extrinsic transconductance was measured. The device with a wider gate width shows a lower peak value, but a slower drop of extrinsic transconductance. This phenomenon is attributed to the influence of polarization Coulomb field (PCF) scattering, which originates from the irregular distribution of the polarization charges at the AlGaN/GaN interface. PCF scattering influences the extrinsic transconductance by scattering the electrons in the gate–source channel, thus altering the source access resistance. Different gate widths are accompanied by different PCF scattering intensities, inducing different behaviors of extrinsic transconductance. It demonstrates the possibility to take advantage of PCF scattering to improve the characteristics of GaN devices.