Thursday, November 11, 2010: 1:00 PM
Seminar Theater (Hilton)
Ternary III-V materials are promising candidates for photoelectrochemical water splitting and high efficiency solar cells. High indium content alloys needed for these applications are however unstable and phase segregation is commonly observed. Nanowires, with their better strain relaxation properties, can reduce phase segregation. Here, we report the results of our initial effort of the MOCVD synthesis of InxGa1-xN alloys on GaN nanowire substrates. Detailed studies of synthesized materials, including structural and chemical characterization of single nanowires in a transmission electron microscope will be discussed. In particular, Energy Dispersive X-ray (EDX) spectroscopy was used to measure the indium concentration in InxGa1-xN alloys and Selected Area Electron Diffraction (SAED) to determine their lattice parameters. The orientation relationship between the alloys and nanowire substrates, the structural quality of the alloys, and structural defects were investigated by means of High Resolution Transmission Electron Microscopy (HRTEM). Our preliminary results confirm that InxGa1-xN can grow epitaxially on GaN nanowires and the growth mechanism will be discussed. Our study indicates also that the lattice parameters of InxGa1-xN increase nonlinearly with the increase of the indium content.