Hall mobility measurements in enhancement-mode GaAs field-effect transistors with Al2 O3 gate dielectric

We report the direct measurement of the inversion charge density and electron mobility in enhancement-mode n-channel GaAs transistors using gated Hall bars. The Hall data reveal the existence of a reduced mobile charge density in the channel due to significant charge trapping. The peak electron mobility was found to be relatively high (∼2140 cm2/V s), in agreement with inherent high carrier mobility of electrons in III-V materials.