Sub-10 nm Nanochannels Enable Directional Quasi-Ballistic Exciton Transport over 5 μm at Room Temperature

Nanoscale potential wells provide a powerful route to engineer energy landscapes in low-dimensional materials, enabling deterministic control over quantum states, carrier dynamics, and optoelectronic responses. Such confinement governs phenomena including charge localization, transport anisotropy, band structure modulation, and light-matter interaction strength. Achieving such precision, however, has been hindered by conventional lithography, which introduces disorder, contamination, or substrate damage. Here, we demonstrate a laser nanomanufacturing approach to fabricate clean, resist-free, and etchant-free dielectric nanochannels in hexagonal boron nitride (hBN), featuring sub-10 nm widths and atomically smooth boundaries with subnanometer roughness. These nanochannels serve as dielectric templates that define programmable energy landscapes for monolayer molybdenum diselenide (MoSe₂), forming excitonic energy funnels that suppress scattering and dramatically extend exciton transport lengths. Exciton transport is transformed from isotropic submicron diffusion into directional superdiffusion with quasi-ballistic propagation exceeding 5 μm at room temperature. The smooth dielectric boundaries further enable precise control over exciton trajectories, allowing for programmable transport pathways. This dry, scalable, and substrate-compatible approach establishes a versatile platform for deterministic exciton engineering and for advancing integrated photonic and optoelectronic devices.