Fermi-level pinning position at the Au–InAs interface determined using ballistic electron emission microscopy

Abstract

Ballistic electron emission microscopy (BEEM) has been used to determine the Fermi-level pinning position at the Au/InAs interface. Using BEEM’s three-terminal capabilities, collector current–voltage scans were taken on Au/InAs/AlSb samples. The extracted BEEM threshold values (1.22 eV) correspond to the highest energy band position in the conduction band at the InAs/AlSb interface. By subtracting the InAs/AlSb conduction-band offset (1.35 eV), an estimate of the Au Fermi-level position on InAs is obtained (0.13 eV).

Formation of strain-induced quantum dots in gated semiconductor nanostructures

“…Sometimes these barriers are due to Schottky barriers; however, the metal-semiconductor pair is often deliberately chosen to prevent a Schottky barrier. For example, in bulk metal-InAs contacts the Fermi level is pinned above the CB, 42,43 and thus a Schottky barrier should not form. Also, many other metal-semiconductor combinations, which form Schottky barriers in bulk, should not form Schottky barriers in a nanostructure, because there are not enough interface states on a nanowire to pin the Fermi level.…”

Current-voltage characteristics of semiconductor-coupled superconducting weak links with large electrode separations

“…The authors recognized the need for very thin semiconductor coupling layers with long electron mean free paths, a combination naturally leading to the investigation of the high-mobility quasi-two-dimensional electron gas in suitable semiconductor heterostructures. Silver et al also recognized the specific advantages of InAs as the semiconductor: The Fermi level at metal-to-InAs interfaces falls inside the InAs conduction band, [19][20][21] thus leading to a freedom from Schottky barriers that would impede the flow of electrons. Most of the subsequent work has indeed used InAs or (In,Ga)As in various configurations; important exceptions are the work of Ivanov et al, 1,2 and more recently of Marsh et al, 7 who employed GaAs-based heterostructures with (superconducting) indium alloy contacts, another combination with very low interface barriers approaching the barrier properties on InAs.…”

Spin and phase coherence lengths in InAs wires with diffusive boundary scattering

“…Diffusive boundary scattering is important in narrow InAs wires due to the fact that surface states pin the Fermi energy E F above the conduction band at the surface of InAs. [24][25][26][27] Hence, unlike in many other III-V semiconductor systems, no depletion layer forms, and the electrons fully sample the boundary roughness. The effect of boundary scattering on spin decoherence in InAs wires may be similar to the effect in narrow metal wires, where experiments demonstrate that the spin decoherence rate is increased by boundary scattering.…”