LASER-PULSE DESORPTION UNDER SCANNING TUNNELING MICROSCOPE TIP-CL REMOVAL FROM SINGLE-SITE ON SI(100)

The desorption of pairs of chlorine atoms influenced by the tip of a s canning tunneling microscope is achieved at preselected sites on the C l-saturated Si(100)-(2X1) surface using nanosecond laser pulse irradia tion of the tip within the tunneling range. Bright features observed f or the empty state topographic images after a laser pulse sequence are interpreted to be due to bare Si-Si dimers formed by laser induced de sorption of two Cl atoms underneath the tip. The Cl desorption mechani sm involves the enhancement of the sample-tip interaction due to laser pulse induced tip heating and tip expansion. (C) 1997 American Vacuum Society.