Self-aligned inversion-type enhancement-mode GaAs metal-oxide-semiconductor field-effect transistor with Al₂O₃ gate dielectric

In this letter, we report fabrication of self-aligned inversion-type enhancement-mode GaAs metal-oxide-semiconductor (MOS) field-effect transistors with atomic layer deposition of Al₂O₃ gate dielectric directly on GaAs substrates using a simple ex situ wet clean of GaAs. Thermal stability of the gate stack was examined by monitoring the frequency dispersion behavior of GaAs MOS capacitors under different annealing conditions. A maximum drive current of ∼4.5 μAμm was obtained for a gate length of 20 μm at a gate overdrive of 2.5 V. The threshold voltage and subthreshold slope were determined to be ∼0.4 V and ∼145 mVdec from the corresponding Id - Vg characteristics.