Adsorption of elemental S on Si(100)2×1: Surface restoration

Adsorption of elemental S at room temperature causes the transition of the reconstructed Si(100)2×{}1 surface to its original bulk-terminated Si(100)1×{}1. The S adsorbate forms initially a (2×{}1) structure at 0.5 ML on the Si(100)2×{}1 surface, a (1×{}1) at 1 ML on the Si(100)1×{}1, and above 1 ML sulfur is imbedded into the Si substrate. The sticking coefficient of S is constant and equal to unity for the first 2 ML. Deposition of S at room temperature up to 1 ML increases the work function by 0.3±{}0.05 eV. The S adsorbate is strongly bound to the Si substrate in a molecular Si-S form. The Si-S bond energy is greater than that of Si-Si, which may be the driving force of the Si(100)2×{}1{→}Si(100)1×{}1 transition.