Metallic-Like Bonding in Plasma-Born Silicon Nanocrystals for Nanoscale Bandgap Engineering

Document Type

Article

Language

eng

Format of Original

8 p.

Publication Date

10-27-2017

Publisher

Royal Society of Chemistry

Source Publication

Nanoscale

Source ISSN

2040-3364

Abstract

Based on ab initio molecular dynamics simulations, we show that small nanoclusters of about 1 nm size spontaneously generated in a low-temperature silane plasma do not possess tetrahedral structures, but are ultrastable. Apparently small differences in the cluster structure result in substantial modifications in their electric, magnetic, and optical properties, without the need for any dopants. Their non-tetrahedral geometries notably lead to electron deficient bonds that introduce efficient electron delocalization that strongly resembles the one of a homogeneous electron gas leading to metallic-like bonding within a semiconductor nanocrystal. As a result, pure hydrogenated silicon clusters that form by self-assembly in a plasma reactor possess optical gaps covering most of the solar spectrum from 1.0 eV to 5.2 eV depending simply on their structure and, in turn, on their degree of electron delocalization. This feature makes them ideal candidates for future bandgap engineering not only for photovoltaics, but also for many nano-electronic devices employing nothing else but silicon and hydrogen atoms.

Comments

Nanoscale, Vol. 8, No. 42 (October 27, 2017): 18062-18069. DOI.

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