Effect Of Nh3 Adsorption On The Atomic-Structure Of Si(111)Root-3 X Root-3-Al And Si(111)Root-3 X Root-3-Ag Surfaces

The room temperature (RT) adsorption of ammonia (NH3) on Si(111) square-root 3 x square-root 3-Al and Si(111) square-root 3 x square-root 3-Ag surfaces has been studied using LEED and AES. The transformation from Si(111) square-root 3 x square-root 3-Al surface structure to Si(111)1 x 1-(Al, H) upon NH3 exposure has been found to be similar to the previously observed structural transformation induced by exposure in the atomic hydrogen. It has been demonstrated that the transformation is caused by hydrogen atoms which are generated by NH3 dissociation on the Si(111) square-root 3 x square-root 3-Al surface. It has been estimated that about 0.1 ML of ammonia molecules is needed to complete the structural transformation. No interaction of NH3 with the Si(111) square-root 3 x square-root 3-Ag surface has been found. The dissociation of NH3 molecules is believed to be impossible on this surface.