The Absolute Coverage of K on the Si(111)-3×1-K Surface

Abstract
The absolute coverage of K on the Si(111)-3×1-K surface which was prepared by deposition of K on the 420°C Si substrate was determined, by using coaxial impact-collision ion scattering spectroscopy, to be 0.29±0.03ML. This result rules out the possibility that the 3×1-K phase is formed by K impurity stabilization claimed by several groups. Another important implication of this result is that K atoms of the 3×1 overlayer are not imaged bright in the STM.