This letter reports on the metal-like conductivity down to 125K in highly crystalline transparent (⩾85% in the visible region) Al:ZnO films grown on sapphire and glass substrates by pulsed-laser deposition technique. Significantly different surface morphologies were found on both types of films. Temperature dependent resistivity measurements of the films grown at 450°C on sapphire and glass show metal-like conductivity with electrical resistivity, ∼1.77×10−4 and ∼3.92×10−4Ωcm, respectively, at room temperature followed by either a residual conductivity or a metal-semiconductor transition at low temperature due to the localization effect caused by the defects.

We report on the significant enhancement of photocurrent in pn heterojunction diode, consisting of n-CdSe∕p-Si substrates, in situ deposited with Au nanoparticles on the surface by the pulsed-laser deposition technique. This is attributed due to the large enhancement in electromagnetic field that occurs in the vicinity of the metal surface, causing surface plasmons. The large enhancement in Raman and photoluminescence intensity was observed due to surface plasmon resonance. Our results suggest that the photodetectors, optoelectronic, such as high-performance thin-film solar cells, optical communication, and sensing devices, including bio- and molecular sensors, can be fabricated with improved functionality.

Al-doped ZnO films were grown on glass substrates by the pulsed-laser deposition technique with varying substrate temperatures. The optical band gap decreases from 3.64 to 3.46 eV as the substrate temperature increases from 350 to 450 • C, illustrating the increase in Al content in the context of a degenerate semiconductor, and can be explained in the framework of the Burstein-Moss effect. All films show optical transparency greater than 85%. Al:ZnO films show a metal-semiconductor transition to metal-like behavior as the substrate temperature increases from 350 to 450 • C. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. The resistivity decreases from 896 to 470 µ cm as the substrate temperature increases from 350 to 450 • C. In addition, the competition between the thermally activated carriers and scattering effects of free carriers in a degenerate semiconductor can also explain the metal-semiconductor transition.

We report chemically synthesized highly crystalline lanthanum strontium manganite ͑LaSrMnO 3 ͒ and Eu-doped Y 2 O 3 and their composites. The synthesis yields nanoparticles of size 30-40 nm. Magnetic measurements performed on nanoparticles and composites show magnetic transition at about 370 K with a superparamagnetic behavior at room temperature. The ferromagnetic resonance studies of the nanoparticles show large linewidth due to surface strains. The composite nanoparticles also display luminescent behavior when irradiated with ultraviolet light. The manganites as well their composite with the luminescent nanoparticles may be very useful for biomedical applications.

We have grown CdSe semiconductor films on glass substrates and the films were coated with Au nanoparticles of 10 nm in size by the pulsed-laser deposition technique. The films demonstrate a large enhancement of Raman intensity and photoluminescence of CdSe semiconductor via excitation of surface plasmon resonances in proximate gold metal nanoparticles deposited on the surface of CdSe film. These observations suggest a variety of approaches for improving the performance of devices such as photodetectors, photovoltaics, and related devices, including biosensors.