SIMULATION OF BULK SILICON-CRYSTALS AND SI(111) SURFACES WITH APPLICATION TO A STUDY OF FLUORINE COVERAGE OF THE SURFACES

Computational efficiency for the simulation of bulk crystals and surfa ces is highly desirable. In an effort to study semiconductor crystals, we present a self-consistent treatment for the simulation of silicon crystals and surfaces based on the combination of a siligen model and a semiempirical Hamiltonian method. An artificial atom called siligen is introduced for the application of the semiempirical method to finit e-size silicon clusters. The calculated average bond energies for the saturated silicon clusters are between 2.045 and 2.568 eV, compared to the measured value of 2.31 eV. A simulated bulk silicon surface using siligens is introduced in order to examine variation of the bond stre ngth between fluorine atoms and the simulated silicon (111) surface. I t is found that bond strength computed from the simulated surface, wit h siligens, rapidly converges to a saturated limit as the number of su rface layers increases, while a pure silicon (111) surface without sil igens yields no satisfactory convergence.