Resonant tunneling of electrons between two-dimensional systems of different densities in a quantizing magnetic field
- PDF / 264,467 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 212 Views
PROPERTIES OF SOLIDS
Resonant Tunneling of Electrons between Two-Dimensional Systems of Different Densities in a Quantizing Magnetic Field V. G. Popova, b, Yu. V. DubrovskiϠ, and J.-C. Portalb, c, d a
Institute of Microelectronics Technology, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia e-mail: [email protected] b Institut National des Sciences Appliquées, F31077 Toulouse Cedex 4, France c Institut Universitaire de France, 103 Boulevard Saint-Michel, 75005 Paris, France d Laboratoire des Champs Magnétiques Intenses, MPI-CNRS BP166 38042 Grenoble Cedex 9, France Received October 3, 2005
Abstract—The results of experimental investigation of the vertical electron transport in a GaAs/Al0.3Ga0.7As/GaAs single-barrier tunneling heterostructure with a doped barrier are presented. Twodimensional accumulation layers appear on different sides of the barrier as a result of the ionization of Si donors in the barrier layer. The nonmonotonic shift of the current peak is found in the I–V curve of the tunneling diode in a magnetic field perpendicular to the planes of two-dimensional layers. Such a behavior is shown to be successfully explained in the model of appearing the Coulomb pseudogap and the pinning of the spin-split Landau levels at the Fermi levels of the contacts. In this explanation, it is necessary to assume that the Landé factor is independent of the filling factors of the Landau levels and is g* = 7.5 for both layers. PACS numbers: 73.21.Fg, 73.43.Jn, 73.43.Lp DOI: 10.1134/S1063776106040182
1. INTRODUCTION Tunneling between two-dimensional systems is very sensitive to the difference between the subband energies. When the subband energies are equal on both sides of the barrier, the tunneling current increases sharply. The bias voltage is a parameter that determines the difference between the subband energies in the tunnel structures. In these structures, the position of current resonance in voltage is determined from the balance equation E 01 ( V r ) = E 02 ( V r ),
(1)
where E01 and E02 are the subband energies, more exactly, the energies of the bottoms of two-dimensional subbands in two-dimensional layers and Vr is the resonance position in voltage or resonance voltage. In the single-particle model of sequential tunneling or in the tunnel Hamiltonian approximation [1], condition (1) can be obtained by taking into account that the total energy and transverse component of the electron momentum in tunneling. It is worth noting that not only coherent tunneling but also tunneling involving scatterers, phonons, and many-particle excitations is of resonance character, which makes it possible to analyze †Deceased.
such effects as tunneling between the Landau levels with different indices [2], optical-phonon-assisted tunneling [3], and the suppression of tunneling near zero bias in strong quantizing magnetic fields or tunneling pseudogap [4–6]. The appearance of the pseudogap was previously studied in detail in tunneling between identical two-dimensional electron systems (2DESs). In this
Data Loading...
