Dimensional Scaling Effect in Percolative Oxide Semiconductor Transistors.

Percolation transport dominates the charge conduction in amorphous and polycrystalline semiconductors. This study identifies a dimensional scaling effect unique to transistors using percolative semiconductors as channel materials, where the materials' percolation threshold (pc) exhibits a strong correlation with the transistor threshold voltage (VT). We demonstrate that both parameters are fundamentally governed by the semiconductor channel geometry. By reducing channel thickness, width, or length, pc is modulated because the availability of conductive pathways is constrained by the channel dimensions, directly driving the observed VT shifts. A quantitative link between pc and VT is established through the percolation potential landscape visualized by scanning tunneling microscopy. The result reveals that the energy landscape is determined by the Fermi level, a characteristic of percolative channels, where device turn-on occurs as the Fermi level exceeds the potential barriers to form conductive pathways. This mechanism is confirmed by temperature-dependent transport measurements, where the extracted activation energies exhibit a strong geometric dependence consistent with the pc and VT shifts. This scaling effect appears consistently in both n-type In2O3 and p-type SnO transistors, showing its universality across percolative semiconductors regardless of the carrier type. These findings demonstrate that transport in amorphous semiconductor devices is defined by percolation-governed transport rather than conventional electrostatics or quantum confinement, and establish geometry as a key design parameter for future amorphous electronics.