Ballistic transport in nanoscale devices

Abstract

Ballistic transport refers to the condition where charge carriers traverse a conductor without scattering, where conduction is governed not by bulk properties but by how electrons are injected, transmitted, and collected at the boundaries. This review gives a unified and critical overview of ballistic transport in a wide range of nanoscale systems such as 1D/2D heterostructures, topological insulators, inorganic heterostructures, molecular junctions (MJs), perovskites, nanowire, nanosheet transistors etc. In these systems, charge carriers move over nanoscale length with near-zero momentum and phase-randomizing scattering. Starting with a historical and conceptual overview of ballistic transport, the conversation explains how the gradual reduction of device sizes below the elastic and inelastic mean free paths fundamentally invalidates diffusive transport models and requires a quantum-coherent description based on transmission eigenchannels, contact-limited resistance, and nonlocal electrostatics. We also discuss the key experimental signatures and theoretical ideas used to identify ballistic behavior, including conductance quantization, length-independent resistance, and nonlocal transport features. Finally, we critically evaluate the significant challenges that hinder the clear identification and technological utilization of ballistic transport and also outline future perspectives that are anticipated to convert ballistic transport from a mesoscopic phenomenon into a foundational principle for next-generation nanoelectronics and quantum devices. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.