Resolving ambiguities in nanowire field-effect transistor characterization

Abstract

We have modeled InAs nanowires using finite element methods considering the actual device geometry, the semiconducting nature of the channel and surface states, providing a comprehensive picture of charge distribution and gate action. The effective electrostatic gate width and screening effects are taken into account. A pivotal aspect is that the gate coupling to the nanowire is compromised by the concurrent coupling of the gate electrode to the surface/interface states, which provide the vast majority of carriers for undoped nanowires. In conjunction with field-effect transistor (FET) measurements using two gates with distinctly dissimilar couplings, the study reveals the density of surface states that gives rise to a shallow quantum well at the surface. Both gates yield identical results for the electron concentration and mobility only at the actual surface state density. Our method remedies the flaws of conventional FET analysis and provides a straightforward alternative to intricate Hall effect measurements on nanowires.

The influence of atmosphere on the performance of pure-phase WZ and ZB InAs nanowire transistors

“…[24,25]. Crucially, because the 2DEG is highly exposed to the surface, the charge distribution and thereby conduction can also be influenced by charged species adsorbed to the outside surface of the nanowire.…”

“…3(b). It is formed by surface-state-induced band-bending, which pins the surface Fermi energy near the conduction band edge [24].…”

Magnetoconductance correction in zinc-blende semiconductor nanowires with spin-orbit coupling

“…In line with the experimental setup of Ref. [30], we consider a length of the nanowire of L = 2.18 μm and a radius of R = 47.5 nm. Moreover, we use the field-effect mobility μ = 600 cm 2 V −1 s −1 and the 3D electron density n 3D = 5 × 10 18 cm −3 .…”

“…More precisely, one is able to effectively control the size, morphology, potential landscape, carrier, and impurity concentration, or even crystal structure [12,[22][23][24][25][26][27][28][29][30][31]. Since typically both the SOC and the WAL/WL correction strongly depend on these characteristics, the great diversity makes it difficult to build up a general theoretical description.…”

“…The WAL/WL effect in the diffusive regime was analyzed by Kettemann [32] and Wenk [33,34] for planar quantum wires with a zinc-blende lattice. In our preceding article [14], we developed a model for diffusive zinc-blende nanowires where the transport is governed by surface states, which occurs in materials with Fermi level surface pinning [12,25,30,35,36] or core/shell nanowires [26].…”