AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS1+MC-ThM

Paper SS1+MC-ThM1
Synthesis and Characterization of Self-assembled Cu@sub2@O Quantum Dots on SrTiO@sub3@(001) Surface

Thursday, October 5, 2000, 8:20 am, Room 208

Session: Oxide Applications and Oxidation
Presenter: Y. Liang, Pacific Northwest National Laboratory
Authors: Y. Liang, Pacific Northwest National Laboratory
D.E. McCready, Pacific Northwest National Laboratory
A.S. Lea, Pacific Northwest National Laboratory
S.A. Chambers, Pacific Northwest National Laboratory
S. Gan, Pacific Northwest National Laboratory
Correspondent: Click to Email
Self-assembled quantum dots have received much attention recently because their atom-like electronic and optical behavior can be tailored. One common problem with many quantum dots has been the poor chemical and thermal stability as most of them are made of conventional semiconductors. An alternative to this problem is to use oxide based quantum dots due to their superior stability. We have successfully synthesized self-assembled Cu@sub2@O quantum dots on SrTiO@sub3@ substrates using a molecular beam epitaxial method. The structure and chemical states of Cu@sub2@O quantum dots have been confirmed by x-ray diffraction and x-ray photoelectron spectroscopy (XPS). Reflection high energy electron diffraction (RHEED), atomic force mic roscopy (AFM), and high-resolution scanning Auger microscopy (SAM) show that formation of Cu@sub2@O quantum dots occurs after deposition of a few monolayers of Cu@sub2@O due to the large compressive lattice mismatches between Cu@sub2@O and SrTiO@sub3@. SAM reveals that the interdiffusion between Cu@sub2@O quantum dots and SrTiO@sub3@ is significantly less than many other quantum-dot systems. XPS further shows that the interfacial electronic structure of Cu@sub2@O/SrTiO@sub3@ exhibits the so-called the type-II heterojunction, i.e., the valance and conduction bands of Cu@sub2@O are both higher than that of SrTiO@sub3@. Consequently the photo-excited electrons and holes are spatially separated with holes being confined to Cu@sub2@O quantum dots and electrons confined to SrTiO@sub3@, a property important for photocatalysis and solar cell applications. We are currently using AFM-based surface potential measurements to elucidate the spatial charge separation behavior of this system upon photo-excitation at different wavelengths. @FootnoteText@ # Pacific Northwest Laboratory is a multiprogram national laboratory operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract DE-AC06-76RLO 1830.