A computer-automated Rutherford backscattering/channeling (RBS/C) system is developed to provide in situ ion beam analysis of the accelerator-TEM system in Wuhan University. The basic system components are a PC equipped with a multichannel analyzer data acquisition board, motion control hardware including the Panmure stepping motor controller and integrated circuit modules, and a Labview programmed operating system with associated electronics. Single crystalline Si(001) and ZnO(001) implanted with Mn ions were characterized with this computerized setup. The crystalline quality 𝜒min and channeling half angle of Si(001) were measured to be 4.65% and 0.52 ∘ , respectively, which are comparable to theoretical values 4.2% and 0.32 ∘ . The ion implantation induced damage depth profile derived from channeling and random spectrum is in reasonable agreement with the result calculated by the SRIM Monte-Carlo simulation code.
BiFeO 3 is a multiferroic material with physical properties very sensitive to its stoichiometry. BiFeO 3 thin films on silicon substrate are prepared by the sol-gel method combined with layer-by-layer annealing and final annealing schemes. X-ray diffraction and scanning electron microscopy are employed to probe the phase structures and surface morphologies. Using Rutherford backscattering spectrometry to quantify the nonstoichiometries of BiFeO 3 thin films annealed at 100 • C-650 • C. The results indicate that Bi and Fe cations are close to the stoichiometry of BiFeO 3 , whereas the deficiency of O anions possibly plays a key role in contributing to the leakage current of 10 −5 A/cm 2 in a wide range of applied voltage rather than the ferroelectric polarizations of BiFeO 3 thin films annealed at high temperature.
We develop a miniaturized chamber installed on a tandetron accelerator into which negative ions of small carbon clusters are transported. Negative clusters C − 1 -C − 10 are obtained with beam currents of 1-10 4 nA at energies of 10-20 keV. C − 2 beams of 0.2 µA are used to directly deposit carbon films on SiO2/Si substrates. Formation of ultrathin carbon films are demonstrated by Raman scattering, which reveals the evolution of the graphitic peak (1550 cm −2 ) with deposition time.
We report on few-layer graphene synthesized on Cu foils by ion implantation using negative carbon cluster ions, followed by annealing at 950 • C in vacuum. Raman spectroscopy reveals I G /I 2D values varying from 1.55 to 2.38 depending on energy and dose of the cluster ions, indicating formation of multilayer graphene. The measurements show that the samples with more graphene layers have fewer defects. This is interpreted by graphene growth seeded by the first layers formed via outward diffusion of C from the Cu foil, though nonlinear damage and smoothing effects also play a role. Cluster ion implantation overcomes the solubility limit of carbon in Cu, providing a technique for multilayer graphene synthesis.
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