Crystallographic Coalescence of Crystalline Silicon Clusters into Superlattice Structures

Abstract

The crystallographic coalescence of crystalline silicon clusters into superlattice structures, generated by direct deposition of a silicon cluster beam on a graphene substrate, has been observed. High-resolution transmission electron microscopy and transmission electron diffraction analyses revealed that adjacent silicon clusters in the superlattices, having a mean diameter of 1.61 ± 0.05 nm (n = 109, n indicating the cluster size, Si n ) and an sp 3 diamond structure, form sp 3 covalent bonds between Si atoms on their surfaces and align their atomic crystalline axes, forming crystallographic rows to coalesce into bcc superlattice structures with a lattice constant of 2.134 ± 0.002 nm. The hcp configuration of the silicon clusters with the same lattice constant as the bcc superlattice unit cell is commensurate with the crystallographic structure of the graphene substrate. The absorption spectra confirm the sp 3 diamond structure of the silicon clusters under well-quantized conditions. Oxygen-free unoccupied electronic states (UDOS) in the conduction band of the silicon cluster superlattices appeared at 99.8 eV in the electron energy loss spectroscopy spectra. The s + d UDOS at 107.5 eV in SiO 2 became conspicuous as the oxidation of the specimen advanced. The collective bulk plasmon loss of the virtually oxygen-free silicon cluster superlattice appeared at 16.7 eV.

Nanoparticle Formation and Deposition by Pulsed Laser Ablation

“…In order to realize such devices, laser ablation remains a promising technology for the future, and worth studied for more possibilities. [45].…”

“…One example is the laser ablation process done in a closed space such as an ellipsoidal cell, in which the collision between the reflected shock wave and the plume front triggers the formation of nanoparticles instantly in a small area [43,44]. The equipment fabricating monodispersed nanoparticles by using this phenomenon is called Spatiotemporal Confined Nanoparticle Source (SCCS), which is illustrated in Figure 6 [45], as the fabrication process is restrained in the confined space and time.…”

“…The possibility of developing new functional materials with nanoparticle films has been pointed out for a long time [46], and many attempts have been made mainly to create light-emitting devices using the visible light emission from silicon Figure 6. Schematic view of new laser ablation-type silicon cluster beam system named SCCS [45].…”

“…Nanoparticle Formation and Deposition by Pulsed Laser Ablation DOI: http://dx.doi.org/10.5772/intechopen.95299 mechanism has been studied [60]. The components of this structure are called silicon nanoblocks [61], which are expected to be applied on next-generation devices such as accumulator integration system with a solar cell [62], ultra-thin supercapacitor [63] and superlattice structures [45]. The silicon clusters possesing atomic crystalline structures generated by SCCS are depositing on the graphene substrate and forming shapes of silicon superlattice as shown in Figure 8.…”

Racetrack-shape fixed field induction accelerator for giant cluster ions

“…This may be a new dawn in both cluster-ion science and accelerator science, opening vistas that nobody has yet dreamed about. Certainly, a RAFFIA would expand the frontiers of materials science that employs giant cluster ions such as C-60 or Si-106 with a super lattice structure [33].…”