| AVS 57th International Symposium & Exhibition | |
| Energy Frontiers Topical Conference | Wednesday Sessions |
| Session EN+NS-WeA |
| Session: | Nanostructures for Energy Conversion & Storage I |
| Presenter: | V.U. Chaudhari, University of Florida |
| Authors: | V.U. Chaudhari, University of Florida D. Wood, University of Florida R. Krishnan, University of Florida T.B. Song, University of Florida T.J. Anderson, University of Florida |
| Correspondent: | Click to Email |
The pseudobinary solid solution GaxIn1-xN alloys exhibits a direct band gap in the range 3.4 to 0.7 eV and thus suitable for optoelectronic device applications. Recent simulations from our group have also suggested this alloy could produce high efficiency thin film photovoltaic devices on the order of 18% efficiency, similar to CIGS devices. The use of nanorod structures for light emitting and absorbing applications promises relatively high junction area, crystalline quality, and collection efficiencies. In addition, the nanorod assemblies are less rigid, and thus open to flexible substrates. The synthesis of nanorods with specific orientation, however, remains a challenge.
The synthesis of self-assembled, vertical InN nanorods and InN-GaN core shell nanostructures on Si without the need for a catalyst or template is reported. This self-catalyzed approach has made it possible to grow nanorods with uniform yet tunable diameter without any patterning of the substrate. The synthesis is performed in a Merged Metal Organic Hydride Vapor Phase Epitaxial growth system. This system allows growth of GaxIn1-xN by either metal organic CVD, using trimethylgallium, trimethylindium and NH3, or hydride VPE in which the metal organic precursor is reacted with HCl. This presentation summarizes properties of the nanorods grown in the temperature range 560 to 600 °C at atmospheric pressure in N2. As revealed by transmission electron spectroscopy, the grown nanorods are defect-free, single crystal showing the wurtzite structure. Scanning electron microscopy and X-ray diffraction results reveal growth in vertical direction with (002) preferred orientation. The InN-GaN core shell structures exhibited a polycrystalline GaN shell with (002) and (101) preferred orientations. This particular behavior of GaN is attributed to the high growth rates used. Annealing studies of these microstructures under ammonia atmosphere showed the absence of alloy formation with virtually no inter-diffusion of In and Ga.