Carrier control and transport modulation in GaSb/InAsSb core/shell nanowires

Abstract

We report transport studies of GaSb/InAs core/shell nanowires. It is shown that with increasing InAs shell thickness, it is possible to tune the carrier concentrations and transport in the structures from p-type (core-dominated) to n-type (shell dominated). For nanowires with an intermediate shell thickness (5–7 nm), we show that the transport is ambipolar, such that an applied top-gate potential can provide further control of carrier type and transport path. In this range, the nature of the GaSb-InAs junction also changes from broken gap (semimetal) to staggered (narrow bandgap) with a small decrease in shell thickness. From a device point of view, we demonstrate that the presence of a thin (<3 nm) InAs shell improves p-type GaSb nanowire transistor characteristics.

Electron-hole interactions in coupled InAs-GaSb quantum dots based on nanowire crystal phase templates

“…The thin, outer passivating InAs shell is omitted here due to a strong confinement-induced shift of these energy levels. 23 Devices with no such outer InAs shell exhibit poor hole transport characteristics. Figure 1(c) shows an SEM image of a core-shell QD NW device, where the positions of the two WZ segments have been indicated.…”

Excitonic condensation in spatially separated one-dimensional systems

“…This is a strong approximation, but current experimental transport data on CSNs show no evidence of Luttinger liquid effects. 24 In particular, metallic InAs nanowires show improved conductance as the temperature is lowered, and there is no evidence of suppression of tunneling into core-shell nanowires at low temperature.…”

“…19,20 We propose that this 'quasicondensation' may be supported in various experimentally relevant condensed matter systems 21 including stacked graphene nanoribbons, 22 in nanowires or carbon nanotubes arranged side-by-side, 23 in a core-shell nanowire (CSN), 24 in nanowires constructed from adjacent electron-doped and hole-doped GaAs quantum wells, or in nanowires patterned from a InAs/GaSb double quantum well. These setups are illustrated schematically in Fig.…”

“…The CSN is a particularly interesting case since it has recently been demonstrated that certain combinations of core and shell materials allow for simultaneous populations of holes in the core region and electrons in the shell region, minimal hybridization between them, and ambipolar transport characteristics. 24 Here, it is reasonable to approximate the low energy band structure in a quadratic form This pair of materials fulfills the general requirements for the excitons to exist: they have bands that overlap with opposite sign of the effective mass. We assume a dielectric constant of ǫ r = 12 in both materials so that the dielectric mismatch is zero and there is no renormalisation of the exciton binding energy.…”

Evolution of morphology and microstructure of GaAs/GaSb nanowire heterostructures

“…[3][4][5]. Furthermore, NW heterostructures, including axial and core-shell structures, can offer us more possibilities on the extent of sophistication of material systems, and this will also accelerate the realization of NW-related applications [6,7].…”