Resonant Tunneling in Nanocolumns Improved by Quantum Collimation

Abstract

We report on a quantum collimation effect based on surface depletion regions in AlAs/GaAs nanocolumns with an embedded resonant tunneling structure. The considered MBE-grown nanodevices have been fabricated by means of a top-down approach that employs a reproducible lithographic definition of the vertical nanocolumns. By analyzing the scaling properties of these nanodevices, we discuss how a collimation effect due to a saddle point in the confining potential can explain an improved device performance of the ultimately scaled structures at room temperature.

MOVPE Self-Assembly and Physical Properties of Free-Standing III-V Nanowires

“…A typical "top-down" approach to the fabrication of epitaxial quasi-1D nanostructures would utilize nano-lithographic techniques, such as electron beam lithography (EBL) and proximal probe patterning, in combination with dry-etching methods to remove excess material from planar epitaxial structures (Wensorra et al, 2005). However, top-down methods do not warrant a sufficiently low dimensionality, the spatial resolution limit of nano-lithographic techniques being typically above the size (20 nm) below which quantumconfinement effects appear in these nanostructures.…”

“…Free-standing nanowires based on III-V compound semiconductors are nowadays in the focus of intense research activities throughout the world; this in reason of the prominent role of these compounds in the optoelectronic arena. Demonstration of resonant tunnelling diodes (Bjork et al 2002;Wensorra et al, 2005), single electron transistors (Thelander et al, 2003;Thelander et al, 2005), and photodetectors (Pettersson et al, 2006) based on quasi-1D nanostructures of III-V compounds have been reported. Also intense single photon sources have been fabricated by embedding InGaP quantum dots in free-standing GaP nanowires (Borgström et al, 2005).…”

R-matrix Formalism for Electron Scattering in Two Dimensions with Applications to Nanostructures with Quantum Dots

“…Both systems are also strongly related to more fundamental research structures developed in the last years, like in-plane-gate transistors [6], single-electron transistors [7], silicon-on-insulator planar double-gate transistors [8], non-planar double-gate FinFETs [9], non-planar trigate transistors [10], nanowire-based fieldeffect transistors (FET) [11], nanowire resonant tunneling diodes [12,13], nanowire lasers [14], or nanowire qubits [15], whose maturity has still to be proven for industrial applications. Their structural complexity has also progressively increased, allowing for double-barrier structures [12,13], or multiple core-shell layers [14,16]. The material composition includes mainly III-V materials GaAs/AlGasAs [6,7,13], InAs/InP [12], GaN/InGaN [14], but also group IV materials Si [4,17], and Si/Ge [11,15], predominant in the industry.…”

“…Their structural complexity has also progressively increased, allowing for double-barrier structures [12,13], or multiple core-shell layers [14,16]. The material composition includes mainly III-V materials GaAs/AlGasAs [6,7,13], InAs/InP [12], GaN/InGaN [14], but also group IV materials Si [4,17], and Si/Ge [11,15], predominant in the industry.…”

Many-body approach to the terahertz response of Wigner molecules in gated nanowire structures

“…As a prototype system, one-dimensional nanowire-based structures [3][4][5] have recently attracted great interest due to their advantageous electrostatics and transport properties. [6][7][8] From a different perspective, they also represent model systems for the study of technological as well as physical challenges in future nanodevice designs.…”