Reactive adsorption and diffusion of Ti on Si(001) by scanning tunneling microscopy

Abstract
Scanning tunneling microscopy has been used to provide the atomic view of the reaction and diffusion of Ti and Si(001) at the monatomic adsorption stage. Two monatomic adsorption structures below and above 440 K have been found. The characteristic adsorption below 440 K is a Ti atom at the pedestal site on a dimer row. The high-temperature adsorption structure above 440 K is adsorption at a dimer vacancy induced by a dimer ejection process on the structural conversion path. The high-temperature adsorption structure shows one-dimensional hopping motion along a dimer row. Measurement of the hop rate gives the activation energy for diffusion and the prefactor of ED=1.8±0.1 eV and νH0=1014±1 sec1, respectively. The growth features and the diffusion mechanism can be interpreted in terms of Ti-Si bond formation.