Laser-induced emission of atoms and electrons from deposited Si atoms on the Si(100) 2x1 surface

We have measured the emissions of electrons and Si atoms induced by laser irradiation on a Si(100) 2x1 surface with Si atoms deposited in a coverage range between 4.6 x 10-4 and 1.67 x 10-1 monolayers (ML) at room temperature. Two types of configurations, referred to as configuration R and S, of deposited atoms are differentiated.. The atom emission from configuration R occurs above a laser fluence of 310 mJ/cm2 for 28-ns laser pulses with a photon energy of 2.48 eV, while that from configuration S occurs only above a fluence of 540 mJ/cm2. The electron emission from configuration R gives rise to a peak at a binding energy of 5.0 eV, while that from configuration S gives rise to a peak at 4.85 eV. Component R grows in proportion to the Si coverage in a coverage range below 4.0 x 10-2 ML and then saturates, while component S grows in proportion to the square of the coverage at initial stage before saturation occurs. The yield of atom emitted from configuration S is reduced only for small coverages. Based on the number of atoms emitted by laser irradiation, the concentrations of configuration R and S after saturation were estimated to be 1.2 x 10-4 ML and 1.94 x 10-3 ML, respectively. It is suggested that configuration R is an adatom weakly bonded by the step edge or a defect and configuration S is an ad-dimer