Size-Selective and Epitaxial Synthesis of GaN, InN, and InxGa1-xN Quantum Dots on Graphite and MoS2 (0001) Surfaces using the Electrochemical/Chemical Method

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This project addresses the synthesis of InxGa1-xN quantum dots(QDs) via a three step electrochemical process. Indium and gallium are co-deposited from aqueous solutions to form nanoparticles of InxGa1-x having a known, average composition followed by electrochemical oxidation of InxGa1-x nanoparticles to form (InxGa1-x)203. The third step involves displacement of the oxide from (InxGa1-x)203 with nitride derived from a reactive source such as ammonia, hydrazine, or hydrazoic acid to form InxGa1-xN QDs and byproducts (gaseous water and hydrogen). Steps 1 and 2 occur at room temperature, and conditions for step 3 will be sought permitting the displacement process to occur efficiently at temperatures below 400C. The approach includes synthesis, as outlined above, and structural characterization and optical characterization of InxGa1-xN QDs. Synthesis parameters will be studied to achieve greater understanding of the processes involved, and to control the particle size mono-dispersity. Optical spectroscopy will be used to guide the synthesis of InxGa1-xN QDs which are luminescent at the bandedge. The PL and absorption properties of these QDs will then be correlated with the indium mole fraction determined using neutron activation analysis. %%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. A variety of fundamental issues are to be addressed in these investigations, and the proposed experiments will also develop a technologically important emissive material which is capable of spanning a large part of the visible spectrum. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***