Semiconductor-Based Nanotechnology Applications.

摘要

This project was based on the PI's research during 2005-2010 as part of a NSF-CAREER award, on the ferromagnetic properties of pure and transition metal doped oxide semiconductors such as SnO2, ZnO, and CeO2, reported in 40 refereed research papers. In this ARO project, studies on ultra small particles of these oxides with crystallite sizes of 2-5nm have shown room temperature ferromagnetism in undoped samples. Interestingly, in oxide nanoparticles doped with transition metal ions such as Fe and Co, the magnetic moment per dopant ion decreased with increasing their concentration, thus suggesting that the magnetic properties are not arising from the dopant ions. The observed magnetic moment in these materials scales with oxygen defect concentration determined from catalytic studies, thus indicating the major role of oxygen defects in the magnetic properties of nanoscale oxide semiconductors. Magnetic Properties of Fe doped, Co Doped and Fe+Co co-doped ZnO nanoparticles showed that charge transfer between co-doped metal ions contributes to ferromagnetism. Thin film structures using Co doped SnO2 were fabricated and studied their usefulness in device applications. NP of semiconducting oxides such as ZnO were also used to investigate their cytotoxicity and preferential cancer cell killing in several types of human cells.