Ballistic transport in nanoscale Si/Ge/SiGe-based devices

The transport properties of charge carriers are fundamental to the investigation of semiconductor physics and nanoelectronic devices. In traditional macroscopic devices, mobility is a critical parameter that characterizes the movement of carriers under an electric field and significantly influences device performance. However, as device dimensions are reduced to scales comparable to the mean free path of carriers, the ballistic transport phenomenon becomes prominent. In this regime, carriers traverse the channel with minimal scattering, rendering the conventional mobility-based drift-diffusion model insufficient. This review seeks to provide a systematic explanation of the characterization techniques for both mobility and ballistic transport, while also analyzing recent advancements and future challenges in Si/Ge/SiGe-based devices.