Comparison for the carrier mobility between the III–V nitrides and AlGaAs/GaAs heterostructure field-effect transistors

Using the measured capacitance-voltage curves of Ni/Au Schottky contacts with different areas and the current-voltage characteristics for the AlGaAs/GaAs, AlGaN/AlN/GaN and In0.18 Al0.82N/AlN/GaN heterostructure field-effect transistors (HFETs) at low drain-source voltage, the two-dimensional electron gas (2DEG) electron mobility for the prepared HFETs was calculated and analyzed. It was found that there is an obvious difference for the variation trend of the mobility curves between the III–V nitride HFETs and the AlGaAs/GaAs HFETs. In the III–V nitride HFETs, the variation trend for the curves of the 2DEG electron mobility with the gate bias is closely related to the ratio of the gate length to the drain-to-source distance. While the ratio of the gate length to the drain-to-source distance has no effect on the variation trend for the curves of the 2DEG electron mobility with the gate bias in the AlGaAs/GaAs HFETs. The reason is attributed to the polarization Coulomb field scattering in the III–V nitride HFETs.