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Synthesis and Characterization at Atomic Level of Novel Nanocrystalline Metal Oxide Structures

EMSL Project ID
5105

Abstract

 This project will focus on two objectives: 1) controllable formation of cooper oxide (Cu2O) quantum dots (QD) using oxygen plasma assisted molecular beam epitaxy (OPA MBE); 2) analysis of grown nanostructures employing the scanning tunneling microscopy (STM) and non-contact atomic force microscopy (NC AFM) alongside with traditional electron spectroscopy techniques.
Quantum dots are promising new structures with potential for application in a wide variety of applications. They often exhibit novel optical, chemical, and electronic properties that can be tailored by controlling their size, composition, and interfacial interactions. Although most investigations on QDs have focused on conventional semiconductors and their electronic and optical properties, the ability to control the formation and interface structure of oxides opens a wide new range of possible materials. Metal oxides represent a class of materials that exhibit promising chemical, optical, electronic, and magnetic properties. Since oxides are often stable in a wide range of environments, the formation of oxide quantum dots can open a new range of possible applications. Cu2O is of considerable interest due to its unique electronic structure, and also evolving potential in chemical and photochemical applications, in particular, water splitting. OPA-MBE will be employed to synthesize Cu2O nanodots with control of the phase and oxidation state by tuning the substrate temperature, oxygen and metal fluxes. Molecular beam epitaxy allows formation of the crystalline heteroepitaxial thin films under well-controlled growth conditions and has been demonstrated to achieve best results for most studied conventional semiconductor system of the Ge nano-dots on Si substrate.
Second objective of this project is to develop an important instrumental capability for structural characterization at atomic level, including on insulating materials, and apply it for investigations of a metal oxide nanostructures. STM has been demonstrated to provide structural at sub-nanometer scale in appropriate conditions. Unfortunately, STM generally has a limited application to oxides due to the conductivity issue. NC AFM can potentially provide similar or complementary information even for bulk insulator oxides. New PNNL state-of-the-art ultra-high vacuum (UHV) variable temperature (VT) STM/NC AFM will be installed and applied for investigation of the morphology and atomic structure of the Cu2O QDs, in-situ grown in the UHV system.

Project Details

Project type
Exploratory Research
Start Date
2003-10-15
End Date
2006-10-04
Status
Closed
Released Data Link
https://search.emsl.pnnl.gov/?project_id_search=5105

Team

Principal Investigator

Zhongqing Yu
Institution
Nanjing Normal University

Related Publications

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Lyubinetsky IV, Z Yu, and MA Henderson. 2007. "Direct Observation of Adsorption Evolution and Bonding Configuration of TMAA on TiO2(110)." Journal of Physical Chemistry C 111(11):4342-4346. doi:10.1021/jp067264d
Wang CM, MH Engelhard, S Azad, LV Saraf, DE McCready, V Shutthanandan, Z Yu, S Thevuthasan, M Watanabe, and DB Williams. 2006. "Distribution of Oxygen Vacancies and Gadolinium Dopants in ZrO2-CeO2 Multi-Layer Films Grown on α-Al2O3." Solid State Ionics 177(15-16):1299-1306. doi:10.1016/j.ssi.2006.05.036
Yu Z, CM Wang, MH Engelhard, P Nachimuthu, DE McCready, IV Lyubinetsky, and S Thevuthasan. 2007. "Epitaxial Growth and Microstructure of Cu2O Nanoparticle/thin Films on SrTiO3(100)." Nanotechnology 18:Art. No. 115601. doi:10.1088/0957-4484/18/11/115601
Yu Z, Y Zhang, CM Wang, V Shutthanandan, IV Lyubinetsky, MH Engelhard, LV Saraf, DE Mccready, CH Henager, P Nachimuthu, and S Thevuthasan. 2007. "Synthesis and Characterization of Compositionally Graded Si1-xGex Layers on Si substrate." Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms 261(1-2):723-726.