The simulation of implantation of heavy charged particles in a crystalline material

9th International Conference on Computer Simulation of Radiation Effects in Solids -- OCT 12-17, 2008 -- Beihang Univ, Beijing, PEOPLES R CHINAWOS: 000271349500039We have studied the channeling effect in the ion implantation by simulating the collision of heavy charged particles with a crystalline material. In order to determine the penetration depth of fast heavy ions in crystalline material, we modified a model from pervious work and studied a situation where heavy As and P ions impinging on a crystal Si surface. A new stopping power calculation method is combined to the transport theory based ion range calculation equation for the fast and accurate numerical calculation of ion ranges. We simulated penetration event by dividing the surface of crystal in to three different region based on the distance from atomic centers in crystal structure. We solved differential equation numerically for each ions simulated. The results have been compared with similar models and the experimental data from literature. We found a good agreement with experiment for the behavior of distribution of ions in the crystalline substance. The model proposed here can be used successfully to predict channeling implantation profiles of heavy ions. (C) 2009 Elsevier B.V. All rights reserved

Z(2) structure of the stopping power for electron beams

4th Conference on Elementary Processes in Atomic Systems -- JUN 18-20, 2008 -- Cluj Napoca, ROMANIAWOS: 000263586200031The target atomic number (Z(2)) dependence of the collision stopping power for electron beams have been investigated for the purpose of determining primary mechanisms in stopping of electrons in elemental matter. The stopping powers of target elements with atomic numbers Z(2) = 1-92 for the electrons have been evaluated on the basis of Gumus method. The variation of the stopping power depending on energy of electrons and type of target has been studied to obtain the elements with the strongest stopping force property for electron beams. A strong Z(2) oscillation in the collision stopping power has been observed whereas the mass collision stopping powers are found to be decreasing with increasing atomic number of the target. It is also found that the electron slowing down in matter mainly depends on the atomic density of target and initial energy of electrons. (c) 2008 Elsevier B.V. All rights reserved.Babes Bolyai Univ, Fac Phys, Hungarian Acad Sci, Inst Nucl Re

Calculation of the electronic stopping cross-sections of compounds for low energy protons by using molecular orbitals

22nd International Conference on Atomic Collisions in Solids -- JUL 21-26, 2006 -- Tech Univ Berlin, Berlin, GERMANYWOS: 000245959300025The modified Firsov model has been applied to the calculation of the electronic stopping cross-section of compounds for low energy protons by using molecular orbitals. We used the Symmetry Adapted Linear Combination of Atomic Orbitals representation of molecular orbitals, instead of Floating Spherical Gaussian Orbitals. We used Gaussian and Slater type orbitals as a basis set of atomic orbitals. By applying this method, the electronic stopping cross-sections of compounds have been calculated by considering compounds as a whole, without separating core and bond orbitals of compounds and the concept of molecular fragments. (c) 2006 Elsevier B.V. All rights reserved