Multilayer phase-coherent tunneling through amorphous MoO₃ barriers in heteromorphic In₂O₃/MoO₃ superlattices

Multilayer phase-coherent tunneling has been demonstrated in a heteromorphic superlattice structure with alternating polycrystalline In₂O₃ conducting layers and amorphous MoO₃ insulating barriers. Unconventional periodic wavefunction with coherent Bloch-like states through multiple disordered barriers is demonstrated. Two methods of transport characterization verify multilayer coherence of this state in samples with varying thicknesses of the MoO₃ layers, namely magnetoconductance (MC) with magnetic field parallel or perpendicular to the superlattice and temperature-dependent conductance. The MC reveals three superlattice weak localization (SLWL) behaviors with decreasing barrier thickness from uncoupled 2D multilayers to “scatter-first-then-tunnel” diffusive Fermi-surface regime, to “tunnel-first-then-scatter” propagative Fermi-surface regime (2D-DFS-PFS). The temperature dependence confirms quasi-2D logarithmic and quasi-3D exponential behaviors consistent with these regimes. Fit parameters including phase coherent length, mean free path, anisotropy coefficient, single-barrier tunnel time, vertical coupling energy are distinguished in each regime, from which evidence of multilayer phase-coherent tunneling is revealed with proper MoO₃ layers thicknesses.