Fabrication and characterization of nanocrystalline CDSE based devices and detection of biomolecular interactions with TMR based sensing using magnetic nanotags

Abstract

The studies presented in this thesis uncovers the novel synthesis methodologies for newlinethe development of nanomaterials and their utilization in suitable applications. newlineNanoparticles (NPs) of CdSe, Hf1-xTixO2 (x = 0-1), and core-shell Ni:NiO were synthesized newlineby a sol-gel type wet chemical synthesis method, and their structural, optical, newlinespectroscopic, magnetic, electrical, and dielectric properties were studied in detail. The newlinegraphitic carbon stabilized CdSe NPs displayed room temperature ferromagnetism (RTFM) newlinealong with optical absorption and emission characteristics. An attempt was made to study newlinethe magneto-optical responses of the derived CdSe NPs by developing CdSe-poly-vinyl newlinealcohol (PVA) nanocomposite films. Doping dependent tunable dielectric properties were newlineobserved in the as-prepared Hf1-xTixO2 NPs. A metal-oxide-semiconductor (MOS) thin film newlinestructure was developed on fluorine-doped tin oxide (FTO) coated glass substrate by newlinedepositing thin layers of HfO2, CdSe, and Aluminum (Al), consecutively by e-beam and newlinethermal evaporation techniques. The dielectric properties of individuals, as well as the newlinestacked layers of HfO2 and CdSe, were studied. In another task, a magnetic tunnel junction newline(MTJ) was fabricated by depositing thin films of Ni and MgO by radio frequency (RF) newlinemagnetron sputtering and e-beam evaporation, respectively, forming Ni/MgO/Ni newlineheterojunction. The structural, morphological, electrical, and magnetic properties of the newlinefabricated tunneling magnetoresistance (TMR) device was investigated. The surfacefunctionalized newlineferromagnetic Ni:NiO NPs tagged to biotin modified single strand (ss) newlinedeoxyribonucleic acid (DNA) oligos were used as nanotags to perform biomolecular newlineinteractions with the complementary ssDNA oligos on the device surface. The change in newlinemagnetoresistance (MR) responses were analyzed to explore the applicability of the TMR newlinedevice as smart biosensors.