Structure determination of the Si3N4/Si(111)- (8 x 8) surface: a combined study of Kikuchi electron holography, scanning tunneling microscopy, and ab initio calculations.

A comprehensive atomic model for the reconstructed surface of Si3N4 thin layer grown on Si(111) is presented. Kikuchi electron holography images clearly show the existence of adatoms on the Si3N40001Si111-8 3 8 surface. Compared with the ab initio calculations, more than 30 symmetryinequivalent atomic pairs in the outmost layers are successfully identified. Scanning tunneling microscopy (STM) images show diamond-shaped unit cells and nine adatoms in each cell. High-resolution STM images reveal extra features and are in good agreement with the partial charge density distribution obtained from total-energy calculations. DOI: 10.1103/PhysRevLett.86.2818 PACS numbers: 61.14.Nm, 61.50.Ah, 68.37.Ef, 77.55.+f