Boron Segregation on the${\rm Si}(111)\sqrt{3} \times \sqrt{3}{\rm R}30^\circ$Surface

In this paper we report the results of calculations of the energies associated with the segregation of boron on the${\rm Si}(111)\sqrt{3} \times \sqrt{3}{\rm R}30^\circ$surface. These calculations have been carried out using the plane wave pseudopotential density functional code fhi98md in a periodic slab formalism. The segregation energy is predicted to be -0.77 eV. This prediction is intermediate between the "experimentally determined" values of -0.33 eV and -0.48 eV, and the values of -1.83 eV and -2.10 eV determined from AM1 cluster calculations. Additional information has been obtained by performingab initiodensity functional cluster calculations using the Gaussian98 code. These latter results indicate that the AM1 calculations significantly overestimate the segregation energy of boron on the${\rm Si}(111)\sqrt{3} \times \sqrt{3}{\rm R}30^\circ$surface. They also provide strong support for the fhi98md calculations.