We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (T s ). The films were found to be crystalline with the electrical resistivity close to 1.1 Â 10 À3 X cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at T s of 400 C, however, a slight decrease in the bandgap was noticed above 400 C, which can be explained by Burstein-Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at $110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels. V C 2013 AIP Publishing LLC. [http://dx

We have demonstrated a simple approach for developing a photovoltaic device consisting of semiconductor-insulator-semiconductor (SIS) heterojunction using surface plasmon polaritons (SPPs) generated in one of the semiconductors (Al:ZnO) and propagated through the dielectric barrier (SiO2) to other (Si). This robust architecture based on surface plasmon excitation within an SIS device that produces power based on spatial confinement of electron excitation through plasmon absorption in Al:ZnO in a broad spectrum of visible to infrared wavelengths enhancing the photovoltaic activities. This finding suggests a range of applications for photovoltaics, sensing, waveguides, and others using SPPs enhancement on semiconductors without using noble metals.

We have demonstrated the fabrication of highly continuous and smooth CdSe semiconductor films containing self-assembled nanocrystals (NCs) using a simple, low cost solution-processed deposition technique. The impact of thermal annealing and ethanedithiol (EDT) treatment on oleate capped CdSe NCs films is illustrated. Post deposition EDT treatment enhances strong electron coupling between NCs by reducing the inter-particle distance, which enhances four orders of magnitude of photocurrent in the pn-device. Mild thermal annealing of NC films cause large redshift and significant broadening. Our findings suggest that NCs with short-range organic ligands are suitable for high-performance Thin-Film-Transistors (TFTs) and next generation high-efficiency photovoltaics.

We demonstrate high performance chemical bath deposited CdS thin-film transistors (TFTs) using atomic layer deposited ZrO 2 based high-k gate dielectric material. Our unique way of isolation of the CdS-based TFTs devices yielded significantly low leakage current as well as remarkable lower operating voltages (<5V) which is four times smaller than the devices reported on CdS-based TFTs using SiO 2 gate dielectric. Upon thermal annealing the devices demonstrate even higher performance, including  FE exceeding 4 ± 0.2 cm 2 V -1 S -1 , threshold voltage V T of 3.8V and I on-off of 10 4 to 10 5 , which hold much promise for applications in future electronic and optical devices.

a b s t r a c tWe report almost perfectly vertically aligned ZnO nanorod arrays synthesized by the hydrothermal route at considerably lower temperature on a sputtered Al:ZnO seed layer using different growth strategies. The nanorod arrays demonstrate remarkable alignment along the c-axis over a large area. Several barrier layers, such as ZnO, Al 2 O 3 , BaTiO 3 and SiO 2 , were introduced to form the p-i-n junction to reduce the leakage current. The photocurrent is significantly reduced in nanorod arrays on AZO/SiO 2 /p-Si heterojunction due to multiple scattering phenomena from ZnO hexagonal facets associated with the nanorod arrays.This research may open up venues for various optical and opto-electronic applications where highly aligned nanostructures are desired.