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Single crystal like TiO(2) nanotubes with preferential orientation along the [001] direction, parallel to the growth direction of nanotubes, that offer ease of charge transport much higher than reported so far, are fabricated using a cost effective two step technique. The success of this method to grow the nanotubes with the anomalous intense [001] preferential orientation is attributed to the zinc assisted minimization of the (001) surface energy. The single crystal like TiO(2) nanotubes show superior performance as supercapacitor electrodes compared to the normal polycrystalline titanium dioxide nanotubes.

Bipolarity with enhanced conductivity has been achieved by tin incorporation in AgInSe 2 thin films. Structural and optical characterizations of these films prepared by reactive evaporation indicate that the incorporation neither distorts the tetragonal chalcopyrite structure nor affects the optical band gap of the parent compound. A detailed analysis of the low temperature conductivity of AgInSe 2 (AIS) and tin incorporated AgInSe 2 (AIS:Sn) suggests domination by variable range hopping, grain boundary effect, and thermal activation of carriers in different temperature regimes. The enhanced conductivity in AIS:Sn is attributed to donor and acceptor defect level formation, which has pushed the Fermi levels to ∼9 meV below the conduction band edge in n-type films and ∼3 meV above the valence band edge in p-type films. These improved characteristics of the films are likely to promote their suitability for photovoltaic and thermoelectric power generation applications.

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