Ab InitioElectronic Properties of Monolayer Phosphorus Nanowires in Silicon

Abstract

Epitaxial circuitry offers a revolution in silicon technology, with components that can be fabricated on atomic scales. We perform the first ab initio calculation of atomically thin epitaxial nanowires in silicon, investigating the fundamental electronic properties of wires two P atoms thick, similar to those produced this year by Weber et al. For the first time, we catch a glimpse of disorder-related effects in the wires--a prerequisite for understanding real fabricated systems. Interwire interactions are made negligible by including 40 ML of silicon in the vertical direction (and the equivalent horizontally). Accurate pictures of band splittings and the electronic density are presented, and for the first time the effective masses of electrons in such device components are calculated.

Ab initio electronic properties of dual phosphorus monolayers in silicon

“…It is easy to envision this coating process being monitored and halted at a desired buffer thickness, before a new δ layer of P is created (and/or patterned). Single δ layer findings [16] suggest that layers interact when less than 80 monolayers (approximately 10.9 nm) of silicon separate them, and that at 80 ML, their properties converge with respect to silicon cladding depth. In that model, periodic replications of the layers were identical by construction, with no possibility of any deviation.…”

“…Whilst single-monolayer studies converge properties by increasingly isolating the layers [11,14,16], at closer separations, it is impossible to divorce specific interactions between two layers from those between all of their (infinite) periodic replications. Further, effects arising due to atomic-scale mismatches in each layer’s doping locations cannot be seen when the neighbouring layer is a perfect replica.…”

“…Further, effects arising due to atomic-scale mismatches in each layer’s doping locations cannot be seen when the neighbouring layer is a perfect replica. Building upon the methodology established whilst investigating single δ layers [16], expanded upon when considering thicker layers comprised of multiple adjacent δ layers [19], and further extended to consider δ -doped nanowires [21], here, we model Si: δ P bilayers, varying both their vertical separation (Figure 1a) and their relative in-plane alignment (Figure 1b).…”

Electronic properties ofδ-doped Si:P and Ge:P layers in the high-density limit using a Thomas-Fermi method

“…These studies used the nemo -d package, 30 which has also been applied to δ-doped Si:P quantum wires. 10,31 Complimentary DFT models of Si:P δ-layers and quantum wires have been proposed using the siesta and vasp packages, with localised atomic orbital (LAO) bases [32][33][34][35] and a planewave basis. 36 However, the applicability of these models to realistic device architectures is restricted by the N 3 scaling in calculation time associated with DFT.…”

Electronic structure of phosphorus and arsenicδ-doped germanium

“…Density functional theory (DFT) calculations on δ-doped germanium are conducted by adapting the general approach previously applied to Si:P by ourselves [16][17][18] and others [19][20][21] to the specific requirements of Ge:P and Ge:As. All calculations are performed using the SIESTA software.…”