Development of p-type transparent semiconducting oxides for thin film transistor applications

Semiconductor physics has developed significantly in the field of re- search and industry in the past few decades due to it’s numerous practical applications. One of the relevant fields of current interest in material science is the fundamental aspects and applications of semi- conducting transparent thin films. Transparent conductors show the properties of transparency and conductivity simultaneously. As far as the band structure is concerned, the combination of the these two properties in the same material is contradictory. Generally a trans- parent material is an insulator having completely filled valence and empty conduction bands. Metallic conductivity come out when the Fermi level lies within a band with a large density of states to provide high carrier concentration. Effective transparent conductors must nec- essarily represent a compromise between a better transmission within the visible spectral range and a controlled but useful electrical con- ductivity [1–6]. Generally oxides like In2O3, SnO2, ZnO, CdO etc, show such a combination. These materials without any doping are insulators with optical band gap of about 3 eV. To become a trans- parent conductor, these materials must be degenerately doped to lift the Fermi level up into the conduction band. Degenerate doping pro- vides high mobility of extra carriers and low optical absorption. The increase in conductivity involves an increase in either carrier concen- tration or mobility. Increase in carrier concentration will enhance the absorption in the visible region while increase in mobility has no re- verse effect on optical properties. Therefore the focus of research for new transparent conducting oxide (TCO) materials is on developing materials with higher carrier mobilities.

Contact potential induced enhancement of magnetization in polyaniline coated nanomagnetic iron oxides by plasma polymerization

The present work derives motivation from the so called surface/interfacial magnetism in core shell structures and commercial samples of Fe3O4 and c Fe2O3 with sizes ranging from 20 to 30 nm were coated with polyaniline using plasma polymerization and studied. The High Resolution Transmission Electron Microscopy images indicate a core shell structure after polyaniline coating and exhibited an increase in saturation magnetization by 2 emu/g. For confirmation, plasma polymerization was performed on maghemite nanoparticles which also exhibited an increase in saturation magnetization. This enhanced magnetization is rather surprising and the reason is found to be an interfacial phenomenon resulting from a contact potential.

Lead free heterogeneous multilayers with giant magneto electric coupling for microelectronics/microelectromechanical systems applications

Lead free magneto electrics with a strong sub resonant (broad frequency range) magneto electric coupling coefficient (MECC) is the goal of the day which can revolutionise the microelectronics and microelectromechanical systems (MEMS) industry. We report giant resonant MECC in lead free nanograined Barium Titanate–CoFe (Alloy)-Barium Titanate [BTO-CoFe-BTO] sandwiched thin films. The resonant MECC values obtained here are the highest values recorded in thin films/ multilayers. Sub-resonant MECC values are quite comparable to the highest MECC reported in 2-2 layered structures. MECC got enhanced by two orders at a low frequency resonance. The results show the potential of these thin films for transducer, magnetic field assisted energy harvesters, switching devices, and storage applications. Some possible device integration techniques are also discussed