AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM6
A New Mechanism of Mo Growth on Au (111) by Chemical Vapor Deposition from a Mo(CO)@sub 6@ Precursor

Tuesday, November 5, 2002, 10:00 am, Room C-110

Session: Diffusion & Growth on Metal Surfaces
Presenter: Z. Song, Brookhaven National Laboratory
Authors: Z. Song, Brookhaven National Laboratory
T. Cai, Brookhaven National Laboratory
Z. Chang, Brookhaven National Laboratory
G. Liu, Brookhaven National Laboratory
J.A. Rodriguez, Brookhaven National Laboratory
J. Hrbek, Brookhaven National Laboratory
Correspondent: Click to Email
Chemical vapor deposition (CVD) of metal carbonyls has been attractive for decades in both making supported metal catalysts and fabricating electronic devices. In most of the previous morphology studies of metal deposition on Au (111), the physical vapor deposition (PVD) method was used to prepare the samples. So far, it is not clear what to expect for the growth of metals from CVD of metal carbonyls. In this study, a Mo submonolayer has been grown by CVD of Mo(CO)@sub 6@ on a reconstructed Au (111) at a substrate temperature of 500 K and studied by STM. The Mo(CO)@sub 6@ molecules decompose on the Au(111) surface at elevated temperatures and form Mo nano-scale clusters. The Mo clusters grow on both upper and lower steps and at elbows of the Au (111) herringbone structure at low coverages. New clusters are formed with increasing Mo coverage and found preferentially within the fcc troughs and randomly at elbows. In contrast to the Mo-PVD, where Mo clusters form well-ordered arrays by decorating all elbows of Au template, the Mo-CVD clusters aggregate without coalescing and develop ramified islands of clusters. An auto-catalyzed carbonyl decomposition is proposed to explain a facile formation of Mo clusters before they anchor on the surface. The Mo growth at upper steps can be attributed to the presence of CO, that modifies locally the surface potential of Mo. This research was carried out at BNL under Contract No. DE-AC02-98CH10086 with the U.S. DOE (Division of Chemical Sciences).