AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoA

Paper SS2-MoA3
Formation of Monodispersed Cobalt Nanoclusters on the Si@sub 3@N@sub 4@(0001)-4x4 Surface

Monday, November 4, 2002, 2:40 pm, Room C-110

Session: Nucleation & Growth of Metals on Oxides & Semiconductors
Presenter: C.-L. Wu, National Tsing-Hua University, Taiwan, ROC
Authors: C.-L. Wu, National Tsing-Hua University, Taiwan, ROC
T.-B. Chou, National Tsing-Hua University, Taiwan, ROC
S. Gwo, National Tsing-Hua University, Taiwan, ROC
W.-C. Lin, National Tsing-Hua University, Taiwan, ROC
M.-T. Lin, National Taiwan University, Taiwan, ROC
Correspondent: Click to Email
A novel phenomenon of forming monodispersed Co nanoparticles at room temperature on a single-crystal Si@sub 3@N@sub 4@ dielectric thin film is presented. Results of very narrow size distributions with an average size of ~30 Co atoms have been obtained. We have found that cobalt clusters deposited on Si@sub 3@N@sub 4@ are stable with respect to cluster agglomeration/coalescence and thermal decomposition. Also, we have confirmed that the average size of Co clusters is independent of the deposition time and insensitive to the magnitude of the deposition flux. Therefore, their areal density can be controlled by the deposition time. The motivation for using a single-crystal Si@sub 3@N@sub 4@ support is two-fold. First, the dielectric support reduces chemical intermixing and electronic coupling (Si@sub 3@N@sub 4@ is an excellent diffusion barrier with a bandgap energy of 4-5 eV) between metal clusters and the substrate compared with situations using semiconductor or metal surfaces. Second, the defect-free Si@sub 3@N@sub 4@ surface provides us a unique opportunity to study the formation of metal clusters without the influence of surface defects. Consequently, quantum effect can play an important role in the size control.