A study on Si nanocrystal formation in Si-implanted SiO₂films by x-ray photoelectron spectroscopy

Abstract

X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy are used to study Si nanocrystal formation in Si-implanted SiO2 films as a function of thermal annealing. Analysis of the XPS Si 2p peaks shows the existence of five chemical structures corresponding to the Si oxidation states Sin+ (n = 0, 1, 2, 3, and 4) in the SiO2 films, and the concentration of each oxidation state is determined quantitatively. The XPS results show a clear picture of the evolution of the chemical structures and the formation of Si nanocrystals as functions of annealing temperature and annealing time. The evolution of the concentrations of the five oxidation states with annealing is explained in terms of the thermal decompositions of the suboxides corresponding to the three oxidation states Sin+ (n = 1, 2, and 3) and the thermal oxidation of the implanted Si.

Compositing Amorphous TiO2 with N‐Doped Carbon as High‐Rate Anode Materials for Lithium‐Ion Batteries

“…According to reports in the literature, [24] the redshifting phenomenon can be ascribed to amorphization of the sample. Therefore, the amorphous nature and nitrogen doping of the a-TiO 2 /C À N hybrid are expected to have an important effect on the electrochemical performance of the hybrid.…”

X-ray Photoelectron Spectroscopic Analysis of Si Nanoclusters in SiO2 Matrix

“…12,13 For chemical characterization, spectroscopic techniques such as IR, Raman, UV-Vis-NIR, X-ray absorption, and X-ray photoemission have been utilized. 14,15 X-ray photoelectron spectroscopy (XPS) is especially powerful due to the perfect match of its probe length with the size of these nanoclusters, and several articles have been published characterizing the silicon nanoclusters, mostly using the chemical shifts to derive information about the nature and the charge state of Si in the nanoclusters and/or the effect of the surrounding matrix on these clusters. [14][15][16][17][18][19][20][21] Since silicon nanoclusters are usually embedded in an insulating matrix, charging is an experimental obstacle to accurate separation of the various chemical/physical parameters contributing to the derived chemical shifts.…”

Characterization of Si Nanocrystals

“…The latter one is clearly related with the recovery of the SiO 2 matrix with annealing. On the other hand, the former one can be related with the nucleation of additional atoms to form nanoclusters since SiÀSi bonds are FTIR inactive [63]. This argument can be further justified since the peak corresponding to the nonstoichiometric SiO x (x < 2) shifts to lower wavenumbers with annealing temperature as it is shown in Figure 21.16a).…”