Real-space nano-imaging of hot electron dynamics

We show the first experimental result of direct hot electron imaging by scanning the local ultra-high frequency 21 terahertz, THz) shot noise at room temperature. In nonequilibrium situations, the local fluctuation of current-carrying electrons (known as shot noise) contains fingerprint-like information of electron kinetics. We use a sharp tungsten tip as a movable, contact-free noise probe to locally detect hot electron kinetics in GaAs/AlGaAs quantum well (QW) nano-devices. Real-space hot electron distribution and nanoscale energy dissipation are directly visualized for the first time. The experimental technique will provide a powerful tool for studying local nonequilibrium dynamics of a variety of phenomena.