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We present a characterization study to develop self-polarized, highly pyroelectric lithium tantalate thin films obtained by RF magnetron sputtering. A preliminary work is done on the bottom electrode to reduce short-term variations of the pyroelectric behavior. Then, the influence of pressure and of deposition temperature is studied to determine the best set of parameters as to obtain a large pyroelectric...
We describe four different photovoltaic (PV) systems that are deployed around Tucson Arizona on geomembranes to test the feasibility of converting mine tailings and landfills into solar energy generating sites. Differences between these deployed systems include: two types of geomembrane materials, two different module anatomies, and two different locations. We explain the different module mounting...
In this paper we present a novel approach to determine material thermal properties of thin film materials. As a test case we have chosen silicon nitride employed in a micro-hotplate structure. We use ANSYS to build a three-dimensional finite element (FE) model of the test structure, which considers heat conduction and convection effects. It is further parameterized and subjected to parametric model...
A micro flow sensor with high temperature coefficient of resistance (TCR) is very important because of its high sensitivity of flow sensors. Different from the conventional positive-TCR Pt film used in micro flow sensor with self-heating, higher negative-TCR micro flow sensor without self-heating is developed and fabricated in this research. The novel TaN-material micro liquid flow sensors are fabricated...
In this paper we report linear and nonlinear optical properties of the thin films based on nanocrystals ZnSe embedded in centrosymmetric matrix PMMA, deposited by spin coating technique. Absorption and emission spectroscopy are shown respectively a blue shift and a strong band emission near the band gap of bulk material ZnSe, which is tunable with particles size. Blue shift of the absorption edge...
In this paper, the method of Spatial Fourier Transform has been used to investigate the pattern formation dynamics in a dielectric barrier discharge (DBD) system. With this method, patterns formed in the DBD system can be transformed into smooth frequency spectrum. The frequency constitution of discharge pattern can be analyzed. In our experiment mixed gas of 96% Ar and 4% air at 0.9 atm is used as...
We present the modification of polydimethylsiloxane (PDMS) surface by titanium dioxide (TiO2) thin film coating and subsequent oxygen plasma treatment. TiO2 thin film was deposited on the prepared PDMS samples by reactive dc sputtering. Pure Ti target was sputtered under a mixture of argon and oxygen plasma, in which the argon to oxygen flow rate ratio is 1:4. Finally, TiO2 coated PDMS structures...
A theoretical model is proposed in this work for an evaluation of the specific heat and Debye temperature of thin-film semiconductors. In the model, the specific heat contributed by the confined acoustic phonons is calculated first. An effective Debye temperature is then defined by fitting the conventional Debye model to the calculated specific heat. It is found that the so-defined Debye temperatures...
The polycrystalline samples of BaSi2, SrSi2, and LaSi were prepared by spark plasma sintering (SPS). The electrical resistivity (rho) and Seebeck coefficient (S) were measured above room temperature. The S of BaSi2 was negative and the absolute values were rather high (-669 muVK-1 at 337 K). The S of SrSi2 was positive and the absolute values were lower (118 muVK-1 at 332 K) than those of BaSi2. For...
Bulk nanostructured (Bi,Sb)2Te3 compounds and GeTe based amorphous/nanocrystal composites have been successfully fabricated by the combined hydrothermal/hot-pressing and quenching/annealing methods, respectively. The (Bi,Sb)2Te3 nanopowders synthesized by hydrothermal method exhibit a hollow-like structure. After hot-pressing, the nanoscale grains varying from tens to hundreds of nanometers were found...
In this study, we fabricated in-plane thermoelectric micro-generators (4 mm times 4 mm) based on bismuth telluride thin films by using flash evaporation method. The thermoelectric properties of as-grown thin films are lower than those of bulk materials. Therefore the as-grown thin films were annealed in hydrogen at atmospheric pressure for 1 hour in a temperature range of 200 degC. to 400degC. By...
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