John Philip

High-temperature ferromagnetism in manganese-doped indium-tin oxide films

High-temperature ferromagnetism is demonstrated in Mn-doped indium–tin oxide (ITO) films deposited using reactive thermal evaporation. These films were grown on sapphire (0001), Si∕SiO2 as well as Si (100) substrates with the highest magnetic moment observed around 0.8μB∕Mn in 5% Mn-doped ITO films. The electrical conduction is n type and the carrier concentration is ∼2.5×1019cm−3 for 5% Mn doping. An anomalous Hall effect is observed in magnetotransport measurements, showing that the charge carriers are spin polarized, revealing the magnetic interaction between itinerant electrons and localized Mn spins. The carrier concentration can be varied independent of the Mn concentration in this transparent ferromagnetic semiconductor for its easy integration into magneto-optoelectronic devices.

Multi-WO3 nanowire based gas detector

The authors have grown high quality WO3 nanowires and fabricated devices with single and multiple nanowires. Devices with single WO3 nanowire exhibit n-type semiconducting behavior and the conductivity increases with hydrogen annealing. The authors also demonstrate significant gas sensitivity of multi-WO3 nanowire devices at room temperature. The sensitivity measurements are carried out in a field-effect transistor geometry with many nanowires connected in between the source and drain electrodes. The sensitivity can be tuned with gate voltages, which will be useful for several applications where controlled gas adsorption is required.