Thermal stability of electrical and structural properties of GaAs-based metal-oxide-semiconductor capacitors with an amorphous $LaAlO3$ gate oxide

We report on thermal stability of the electrical and structural properties of metal-oxide-semiconductor capacitors with amorphous $LaAlO3$ high dielectric constant (high $k$⁠) oxide on GaAs epitaxial layers with and without an interface amorphous silicon $(a-Si)$ passivation layer to prevent Fermi level pinning at the III-V/high-$k$ interface. The electrical properties of $a-Si$ passivated GaAs improved with annealing temperature, demonstrating reduced equivalent oxide thickness, small $(∼50mV)$ hysteresis of capacitance-voltage characteristics, and low interface state density $(⩽2×1011eV−1cm−2)$⁠. Transmission electron microscopy with x-ray microanalysis revealed densification of the amorphous $LaAlO3$ and its reaction with an oxidized $a-Si$ layer.