Narrow Results

Using a simplified model, the surface energy of the Si/SiO2 interface in silicon nanowires (SiNWs) is derived. Our theoretical results show that the nanowires along <112> and <110> have very low surface energy, so their yields should be high. Experimental observation testifies that the SiNWs fabricated by the oxide-assisted growth (OAG) are mostly of these two orientations. This supports the consideration that during growth process, surface energy is the chief factor to determine the axis orientation of nanowires under OAG.

The deformation behavior of the nanocomposite structure under tension was studied by molecular dynamics (MDs) simulation. This nanocomposite structure is called as SiNW@CNT, which is a silicon nanowire (SiNW) embedded in carbon nanotube (CNT). The simulation results show that the insertion of the SiNW into CNT increases the tensile strength of zigzag CNT and the maximum tensile strain of the armchair CNT. However, it can greatly reduce the maximum tensile strain of the zigzag CNT and the maximum tensile strength of the armchair CNT. In addition, the maximum tensile strain of the SiNW@CNT has little to do with the diameter of the CNT, but is mainly related to the chirality of the CNT. For both hollow CNT and SiNW@CNT, the tensile strength is related to the diameter and chirality, and smaller diameter but greater tensile strength. This findings suggest that the physical properties of the SiNW@CNT can be tailored to specific applications by controlling the CNT diameter and chirality.

The optical properties of the various types of tapered silicon nanowires (SiNWs) have been investigated by the phase retrieving method of utilizing the experimental reflection spectra with the aid of the Kramers–Kronig (KK) relation. The effective refractive index (n) and the extinction coefficient (K) of each tapered SiNWs and combined silicon nanowires and microwires (CNMW) array samples can be obtained from concrete simulation by the KK relation. At the same time, we can also obtain the real part (ε′) and imaginary part (ε″) of the effective complex dielectric constant from the relation between the refractive index and the complex dielectric constant of samples. And the simulated results show that the relative material parameters (effective complex refractive index, effective complex dielectric function) can be modulated from a concrete material processing.

We present CMOS compatible fabrication technique for silicon nanowire (SiNW) on bulk silicon wafers. Our method uses saw-tooth etch-profiles of fins followed by self-limiting oxidation to form vertically self-aligned horizontal SiNW down to 5 nm diameter. The concept of modifying the cross-section shape of SiNW from triangular to circular and the ability to achieve desired nanowire diameter are unique in this work. Nanowires formed by such technique can be utilized to realize several nanoelectronics devices like gate-all-around transistor, single-electron-transistor, etc.; NEMS and bio-medical sensors; all in a CMOS friendly manner. The physical and electrical characterization of the SiNW is also presented in this paper.

Top-down silicon nanowire (SiNW) fabrication mechanisms for connecting electrodes are widely utilized because they provide good control of the diameter to length ratio. The representative mechanism for the synthesis of SiNWs, a top-down approach, has limitations on the control of their diameter following lithography technologies, requires a long manufacturing process and is not cost-effective. In this study, we have implemented the bottom-up growth of horizontal SiNWs(H-SiNWs) on Si/SiO₂ substrates directly by plasma enhanced chemical vapor deposition (PECVD) under about 400°C. The HAuCl4 solution as a catalyst and SiH₄ gas as a precursor are used for the synthesis of H-SiNWs. After optimization of synthesis conditions, we evaluated the photoelectric properties of the H-SiNWs under illumination with different light intensities. Further, we demonstrated the feasibility of H-SiNW devices for the detection of biotinylated DNA nanostructures and streptavidin interaction.

Because the motion of charge carriers in nanowires and quantum dots is restricted within nanoscale in two and three dimensions, respectively, both nanowires and quantum dots exhibit many excellent optoelectronic properties. Particularly, with the advantage of being compatible with Si integrated circuits, Silicon nanowires (SiNWs) and germanium quantum dots (GeQDs) have been extensively studied in the past few decades. In order to explore novel physical properties, the integration of SiNWs and GeQDs has attracted great attention recently. In this paper, recent researches on the preparation methods and structures of SiNWs, GeQDs and their composites are reviewed, respectively. The synthesis of SiNWs with random distribution and ordered arrays by using vapor–liquid–solid growth mechanism and metal-assisted chemical etching technique is firstly summarized. Some special structures of SiNWs are also discussed. Furthermore, the development of some novel structures of GeQDs for further improving their optical properties is reviewed. Finally, the growth mechanism and structure evolution of SiNWs/GeQDs composites are illustrated from the view of theory and experiment. The strain in Ge shell layers and SiNWs, the relationship between Ge growth mode and SiNW diameter, and the distribution of GeQDs on the radial and axial directions of SiNWs are discussed in detail. The research about the growth of SiNWs/GeQDs composite structures is in its early stage, so there are many questions that need to be resolved in future.

To reveal the relationship between the electronic structure, the lattice dynamics and the thermoelectric properties of silicon nanowire (SiNW) the first-principles calculations of SiNW and silicon bulk (SiB) were conducted in this work by using density functional theory and Boltzmann transport theory. The results indicate that the electrical conductivity of SiNW is increased significantly while its thermal conductivity is reduced sharply as compared to those of SiB, which consequently results in a large enhancement in the figure of merit (ZT) of SiNW at 1200 K. We attribute the increase in the electrical conductivity to the increased density of states at Fermi energy level and the transition from a semiconductor to semimetal behavior. Moreover, the remarkable reduction in the thermal conductivity is resulted from the weakened covalent bonding, the decreased phonon density of states and the shortened mean free path of phonons.