Electron tunneling through semiconducting barriers

Abstract

Metal-doped semiconductor-metal tunnel junctions for which the tunneling barrier is made of a double Schottky barrier are proposed and studied both experimentally and theoretically. Using the tunneling barrier model, the electron tunneling current is calculated. The junctions are prepared by successive condensation from vapor of a P b electrode, a CdS layer, and 5~ second P b electrode. The thickness of the semiconducting layer is varied from 50 t o 5000 A. The I-U characteristics of the junctions are measured a t liquid helium temperature and prove to be in good agreement with the theory proposed.Xous avons propose et Btudi6 tant thboriquement qu'expi.rlmentalement, des jonctions tunnel, metal-semi-conducteur (dop&)-metal, pour lesquelles la barrihre tunnel est constituee d'une double barribre Schottky (deux contacts metal-semi-conducteur accoles dos A dos). Nous avons calculh pour ce modble de barrikre le courant tunnel. De telles jonctions ont Bte rbalishes par evaporation thermique, l'bpaisseur de la couche semiconductrice (CdS) variant de 50 & 5000 A. Les caractbristiques blectriques de ces jonctions ont 6tb mesnrkes aux temperatures de l'hblium liquide. Les rbsultats exphrimentaux sont en accord avec les conclusions de la thhorie proposbe.

Crossover from diffusive to tunneling regime in NbN/DyN/NbN ferromagnetic semiconductor tunnel junctions

“…We found that the Simmons rectangular tunnel barrier model does not fit to these nonlinear I -V curves. Due to large conductivity mismatch between DyN and NbN, Schottky barrier is expected at the interface between DyN and NbN [6,19]. The resulting Schottky contact at the two interfaces forms two triangular-shaped Schottky barriers with narrow depletion width.…”

Influence of Resonance Tunneling on Resistivity in Semiconductors With Ionized Impurities and on Tunneling Current Between Superconductors

“…U < E,, the "left" barrier height). For the '5deal"Schottky barrier, the potential energy @(x) in the junction is then given by [6] where J1, it2 are the widths of the depletion zones defined by E is the static dielectric constant of the semiconductor, N the donor or acceptor density, L the thickness of the semiconductor, x the distance from the "left" metalsemiconductor interface, Ul = eVl, U2 = eV2 (Vl, V2 are the potential differences between metal and semiconductor), with U, + U, = U = eV ( V is potential difference between both metals). The energy is measured from the Fermi energy of the "left" metal.…”

“…Using the method of the tunneling Hamiltonian and of perturbation theory, one can describe the amount of electrons R A , B which cross from the "left" superconductor (label A) to the "right" superconductor (label B) per time unit [21] by 4n R A , B =- , k l z { u ; A u ; B ( lf p A -f k B ) S ( E p A + E preparation of such junctions was described in [6], where an approximate expression for the tunnel current was derived a t larger voltages, where the junction is essentially a single Schottky barrier. For lower voltages, a t which the junction is still a DSB, resonances appear in the tunneling probability.…”

“…semiconductors [6] and even in biological systems (transmission of ions through the bilipides of membranes) [7].…”

“…We expect similar fundamental changes in tunneling between two superconductors separated by a double barrier (e.g. by a double Schottky barrier -DSB) [6]. The method taking into account the changes of the barriers with the applied electric field was worked out in [6, 171.…”