Lateral electron tunneling spectroscopy between low-dimensional electron systems in GaAs/AlGaAs heterostructures. Beiträge zur Nanoelektronik Bd. 9 Pb., 156 S., 52 Abb., 7 Tab.
In this work, we accomplished lateral electron tunneling spectroscopy between low-dimensional (two-dimensional, 2D, or one-dimensional, 1D) electron systems in a GaAs/AlGaAs heterostructure by preparing a thin barrier using atomic force microscope lithography. Three kinds of electron tunneling devices were fabricated: a 2D-2D, a 2D-1D and a 1D-1D tunneling device. In each device, we performed transport spectroscopy and tunneling spectroscopy at a temperature of 4.2 K. The tunneling conductance as a function of the applied bias of the 2D-2D device shows Fermi-edge effects revealing the 2D electron gas density. Magnetodispersion spectra depicts tunnel coupling between counter-propagating Landau levels. In the 2D-1D device, the 1D electron waveguide (EWG) exhibits quantized conductance for gate voltages below the onset of tunneling. Energy separations of 1D-subbands up to 5.4 meV were determined. The oscillatory structure of the tunneling conductance is attributed to the sharp nature of the 1D electron density of state (DOS). The 1D-1D device consists of two parallel EWGs separated by a tunneling barrier. In both the transport spectroscopy along each waveguide and the tunneling spectroscopy across the barrier, we observe clear evidence of 1D-wavefunction mixing. Anticrossing energy spacings of 2.6 meV and 2.2 meV have been estimated from the first and the second spectroscopy technique, respectively.