A Comprehensive Study of Electron Energy Losses in Ge Nanowires

Abstract

We present a comprehensive study of electron energy losses by fast electrons that occur in isolated single-crystal Ge nanowires with organic monolayer-passivated surfaces. A ∼0.5 nm diameter electron probe in a scanning transmission electron microscope equipped with an energy loss spectrometer (STEM-ELS) was used to study plasmon and core electron excitations. Losses due to scattering from volume and surface plasmons vary with respect to the probe position relative to the nanowire surface, and the volume plasmon energy increases with decreasing diameter for nanowires narrower than 24 nm. Below 24 nm, the organic monolayer-coated nanowires also exhibit size-dependent Ge 3d core ionization spectra that shift to higher energy with reduced diameter that are independent of probe position relative to the surface. In contrast, the Ge 3d edge for surface-oxidized nanowires exhibits a chemically induced shift when positioned near the surface.

Ab initio energy loss spectra of Si and Ge nanowires

“…3 and 4 is due to the fact that the diameters of our computed NWs are much smaller than those used in the experiments. 28.) 5 we report the computed energetic positions of the high energy EELS peak as a function of NW size, together with experimental measurements ascribed to the volume plasmon (at o pl ) as reported for Si 27 and Ge 28 NWs of larger diameters.…”

“…The most used methodology is the vapor-liquid-solid (VLS) mechanism, in which a catalytic nanoparticle, normally Au, is used to promote the decomposition of an appropriate gaseous precursor. Interesting and particular features have been observed in the EELS spectra of semiconductor NWs (including Si and Ge NWs) as well as in C, BN, and WS 2 nanotubes, [26][27][28][29][30][31][32][33] and are believed to derive from the reduced dimensionality of these systems. The diameter of the NWs depends on the orientation: the smallest (a few nanometers) are obtained, usually, for the h110i direction; the largest for the h111i direction; and intermediate ones, about 10 nm, for the h112i direction.…”

Application of Aberration-Corrected TEM and Image Simulation to Nanoelectronics and Nanotechnology

“…It is now well known that electron diffraction patterns of nanowires are known to exhibit extra diffraction spots [22]- [24]. In Fig.…”

From nanoparticle to nanocable: Impact of size and geometrical constraints on the optical modes of Si/SiO2 core/shell nanostructures

“…The SREELS performed in a transmission electron microscope ͑TEM͒ not only allows the investigation on individual nanostructures, providing information on both single electron excitations and collective electron oscillations, but also enables the study on the spatial distribution of specific excitations. 15,16 In addition to the experimental investigation, theoretical simulations have also been carried out on the two specific configurations, i.e., the spherical particle and cylindrical cable, to explain the possible origin of the observed optical extinction modes in the nanocables.…”