Effects of incident N atom kinetic energy on TiN/TiN(001) film growth dynamics: A molecular dynamics investigation

摘要

Large-scale classical molecular dynamics simulations of epitaxial TiN/TiN(001) thin film growth at 1200 K, a temperature within the optimal range for epitaxial TiN growth, with an incident N-to-Ti flux ratio of four, are carried out using incident N energies E_N = 2 and 10 eV and incident Ti energy E_(Ti) = 2 eV. To further highlight the effect of E_N, we grow a bilayer film with E_N = 2 eV initially and then switch to E_N = 10 eV. As-deposited layers are analyzed as a function of composition, island-size distribution, island-edge orientation, and vacancy formation. Results show that growth with E_N = 2 eV results in films that are globally overstoichiometric with islands bounded by N-terminated polar 110 edges, whereas films grown with E_N= 10 eV are flatter and closer to stoi-chiometric. However, E_N = 10 eV layers exhibit local N deficiency leading to the formation of isolated 111-oriented islands. Films grown by changing the incident energy from 2 to 10eV during growth are more compact than those grown entirely with E_N = 2 eV and exhibit greatly reduced concentrations of upper-layer adatoms, admolecules, and small clusters. Islands with 110 edges formed during growth with E_N = 2eV transform to islands with 100 edges as E_N is switched to 10 eV.