Si(111): SiH3—A Simple New Surface Phase

Photoemission spectra show that atomic hydrogen reacts near room temperature with Si(111)1×1 to form a trihydride phase, Si(111): Si${\mathrm{H}}_3$. The new phase, clearly to be distinguished from the monohydride Si(111): H obtained from Si(111)7×7, has been identified by theoretical calculation of the photoemission spectrum. Formation of Si(111): Si${\mathrm{H}}_3$ suggests that the vacancies that exist on clean Si(111)7×7 are disordered on Si(111)1×1.