Figure 3

Hot-electron emission and transport. (a) A false-colour SEM image of a hot-electron time-of-flight measurement device [79]. The red and blue arrows show two paths taken by the electrons emitted by a quantum-dot pump at the left. The difference in arrival times from the two paths are used to estimate the drift velocity. The two-dimensional electron gas in the paths are depleted by a surface gate. (b) A schematic of Landau levels near the edge where the two-dimensional electron gas is depleted. “Usual” edge states forming near the Fermi energy are indicated by black circles. The high-energy states where hot electrons travel are indicated by a red circle. (c) Energy diagram of hot-electron emission from an electron pump (blue-coloured potential on the left) and its detection by energy-dependent barrier (red-coloured potential on the right). (d) The determination of the electron emission energy \(E_{\mathrm{{1}}}\) by the measurement of transmitted current as a function of the detector barrier height [72]. f is the operating frequency of the electron pump