Fractal pattern evolution of NiSi2 grains on a Si surface was induced by high current pulsed Ni ion implantation into Si wafer using metal vapor vacuum arc ion source. The fractal dimension of the patterns was found to correlate with the temperature rise of the Si substrate caused by the implanting Ni ion beam. With increasing of the substrate temperature, the fractal dimensions were determined to increase from less than 1.64, to beyond the percolation threshold of 1.88, and eventually up to 2.0, corresponding to a uniform layer with fine NiSi2 grains. The growth kinetics of the observed surface fractals was also discussed in terms of a special launching mechanism of the pulsed Ni ion beam into the Si substrate.

Cheng X. Q.;Zhu H. N.;Liu B. X.

Materials Research Society Symposium Proceedings

2001

The synthesis of Yttrium disilicide films on silicon wafers through Yttrium ion implantation using a metal vapour vacuume arc ion source was investigated. A crystallized hexagonal structured film was obtained. The phase formation mechanism of YSi2 was discussed with respect to temperature elevation due to ion beam heating and the ion dose in the process of ion implantation. This technique was found to be good for synthesis of the rare earth metal silicides.

Wang R. S.;Cheng X. Q.;Lai W. S.;Liu B. X.

Journal of Physics D Applied Physics

2001

In the Ni-Mo system, two possible nonequilibrium states located near Ni 3 Mo were predicted through calculation of the total energies of eight possible structures of the A 3 B type as a function of their lattice constant(s) by applying the Vienna ab initio simulation package. Comparatively, Gibbs free energy diagrams were constructed from Miedema's model and, in general, the calculated results were in accordance with the prediction from ab initio calculation. Besides, the prediction of one of the nonequilibrium states was in agreement with the fact that a metastable hexagonal-close-packed Ni 3 Mo phase was indeed observed in Ni 75 Mo 25 multilayer films upon thermal annealing, and calculated lattice constants matched well with those determined by diffraction analysis in experiments as well.

Liu J. B.;Zhang R. F.;Liu B. X.

Journal of Materials Research

2002

Continuous NdSi2 phase layers could be obtained by high-current Nd-ion implantation into Si using a metal vapor vacuum are ion source and the formation temperature could be relatively low in the range from 165 to 320°C. Furthermore, the surface morphology of the Nd-ion implanted surface varied with the implantation parameters. The formation mechanism of the NdSi2 phase as well as its continuous layer is also discussed in terms of the temperature rise caused by ion beam heating and variations of the ion dose in the Nd-ion implantation process.

Cheng Xiang Qian;Wang Run Shun;Liu Bai Xin

Japanese Journal of Applied Physics Part 1 Regular Papers and Short Notes and Review Papers

2002

Employing the Vienna ab initio simulation package (VASP), calculation results predicted that three nonequilibrium phases with D0 19 , L1 2 and A15 structures were energetically favored to be formed at a stoichiometry of YTa 3 in the equilibrium immiscible Y-Ta system. Experimentally, ion-beam mixing of the YTa 3 multilayers did result in respective hcp and fcc YTa 3 phases, yet failed to obtain an A15 one because of the kinetic constraint. Moreover, the lattice constants of the formed nonequilibrium phases were in good agreement with the calculated values.

Liu Jian Bo;Liu Bai Xin

Japanese Journal of Applied Physics Part 2 Letters

2002

Using a metal vapor vacuum arc ion source, plain and continuous ErSi2 layers of good crystalline structure were formed on Si surfaces by high current Er-ion implantation. Interestingly, under some specific conditions, the formed ErSi2 grains organized themselves in a fractal pattern featuring self-similarity. The mechanism of the ErSi2 formation as well as the growth of the fractal pattern was discussed in terms of the dynamic launching of energetic Er ions into Si, beam heating effect, and the effect of ion fluence during the high current Er-ion implantation of far-from-equilibrium. © 2002 Elsevier Science B.V. All rights reserved.

Cheng X. Q.;Liu B. X.

Journal of Alloys and Compounds

2002

PrSi2 layers were fabricated on Si wafers with metal vapor vacuum arc ion implantation without in-situ-heating or post-annealing. Under optimal experiment conditions, the obtained PrSi2 layers were of good crystalline structure and featured plain and continuous morphology. In addition, the formation mechanism of the PrSi2 layers is also discussed in terms of the temperature rise caused by ion beam heating as well as the variation of ion implantation dose. © 2002 Elsevier Science B.V. All rights reserved.

Cheng X. Q.;Liu B. X.

Journal of Alloys and Compounds

2002

Ab initio calculations were carried out by means of the Vienna ab initio simulation package (VASP) to predict the possible nonequilibrium states in the Co-Mo system. At the composition of Co 3 Mo and CoMo 3 , the total energies are calculated for the four different structures, i.e. A15, D0 19 , L1 2 , and L6 0 , as a function of the lattice constant and some possible nonequilibrium states in the Co-Mo system are predicted, i.e. at a stoichiometry of Co 3 Mo with D0 19 structure and at CoMo 3 with an A15 structure. Experimentally, ion beam mixing of Co-enriched Co-Mo multilayers has resulted in the formation of a metastable hcp phase, which is in accordance with the predicted Co 3 Mo state and its crystalline structure as well as total energy. © 2003 Elsevier Science Ltd. All rights reserved.

Guo H. B.;Kong L. T.;Liu J. B.;Liu B. X.

Solid State Communications

2003

The Al3Hf phase was formed by Hf ions implantation into Al film with a current density of 64 μA/cm² to a dose of 7 × 10¹⁷ ions/cm² using a metal vacuum vapor arc ion source. The surface hardness of Al film increased after Hf ions implantation. The quantitative depth profile of the formed Al3Hf phase was obtained using the quantitative structure and phase depth profiling technique of X-ray diffraction patterns. In the surface layer of the sample, the content of Al3Hf phase was about 67%. With the increase of depth, the content of Al3Hf phase decreased. At the bottom of the Al film the content of Al3Hf phase was about 5%. © 2003 Elsevier Science Ltd. All rights reserved.

Miao Wei;Tao Kun;Liu Xingtao;Li Bin;Liu Baixin

User Modeling and User Adapted Interaction

2003

Using a metal vapor vacuum arc ion source, continuous and stable MoSi2 films were directly obtained by high current Mo-ion implantation into Si wafers with neither external heating nor post-annealing. Interestingly, under some specific conditions, the formed MoSi2 grains organized themselves in fractal patterns featuring unique self-similarity. The mechanism responsible for the MoSi2 formation as well as the growth of the fractal pattern is discussed in terms of the dynamic launching of the energetic Mo ions into Si, ion beam heating effect, and the effect of ion dose during high current Mo-ion implantation of far from equilibrium. © 2003 Elsevier Science B.V. All rights reserved.

Cheng X. Q.;Wang R. S.;Tang X. J.;Liu B. X.

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms

2003