U. Sivan

HOT ELECTRON TRANSPORT IN TWO DIMENSIONAL ELECTRON GAS

Abstract We demonstrate ballistic transport of hot electrons in a high mobility two dimensional electron gas (2DEG) over distances as large as two micrometers and tunneling through a barrier induced in the 2DEG. Various inelastic scattering mechanisms are studied experimentally. For electrons with excess energy larger than the longitudinal optical (LO) phonon energy quanta we show sequential emission of up to three phonons. Below that energy we find a surprisingly long mean free path, approximately an order of magnitude longer than expected theoretically for electron-electron scattering. The combination of a very short mean free path for LO phonon emission and the long mean free path below the phonon energy leads to a new type of periodic oscillations in the maximal energy of the collected electrons. Finally we report on a study of the angular distribution of hot electrons injected from a point contact and demonstrate electrostatic steering of the electronic beam.

Lateral tunneling and ballistic transport in two‐dimensional electron gas devices defined by nanostructure gates

Novel, laterally configured, tunneling hot electron transfer amplifier (THETA) devices have been formed using nanostructure metal gates to induce potential barriers separating emitter, base, and collector regions in a two‐dimensional electron gas. The gates were formed by a liftoff technique using PMMA resist and a high resolution electron beam writing tool. Lateral electron tunneling has been directly observed, using electron energy spectroscopy, through potential barriers under metal gates as wide as 52 nm. The energy distribution of the hot electrons was only ≂5 meV wide. Certain gate configurations were found to increase the fraction of emitted electrons which reached the collector. Current gain as high as 105 was observed. This is better than the best results previously obtained with vertical THETA devices.

Hot electron transport in the plane

Abstract We summarize recent experimental results of hot electron transport in the plane of a high mobility two-dimensional electron gas. We find long mean free paths, much longer than is expected theoretically.