In this thesis study, fabrication and characterization of silicon thin films prepared by magnetron sputtering and electron beam evaporation for solar cell applications have been investigated. In the first part of the study, magnetron sputtering method was used to fabricate thin hydrogenated amorphous silicon (a-Si:H) film on a Si substrate. Some samples were prepared on glass substrate for the basic characterizations like transmission and resistivity. Dark and illuminated I-V characteristics of the silicon heterojunction (SHJ) solar cells were studied as a function of material type and process parameters. It was observed that devices show diode characteristics, however their response to the illumination was quite weak. Low performance of the devices was discussed in terms of the resistivity and dopability of the sputtered film. The second part of the thesis deals with the fabrication and characterization of thin polysilicon films fabricated by e-beam evaporation. In order to dope the deposited Si films, a very thin boron film v was deposited by e-beam evaporation on SiO2 surface thermally grown on a Si wafer. Then an a-Si was evaporated by the same technique. Samples were annealed for polysilicon formation by using the technique called solid phase crystallization (SPC). The annealing was performed in two steps. The first step was the nucleation part, carried out at 475&deg / C for 8 hours and the second step was the diffusion and crystallization parts that are accomplished at 900&deg / C for several minutes. The Raman measurements revealed out the crystallinity and grain size. The crystallinity of the polysilicon thin films was also identified by X-Ray diffraction measurements. Finally, the Secondary Ion Mass Spectroscopy (SIMS) analysis was carried out to find out the amount of boron that diffuses into Si film. It was found that a graded boron profile, which is desirable for the solar cell applications, was achieved.

In this dissertation, the ternary Mg-based amorphous ribbons are characterized and analyzed first. Among the three Mg65Cu25Y10, Mg65Cu25Gd10 and Mg65Ni25Gd10 amorphous ribbons, the Mg65Cu25Gd10 amorphous ribbon exhibits the best thermal properties in terms of the glass forming ability (GFA) indexes, such as 68 K of the supercooled liquid region (£GTx), 29 K of the liquidus region (£GTl), 0.582 of the reduced glass transition temperature (Trg), 0.427 of the £^ value and 0.768 of the £^m value. In spite that the Mg65Cu25Gd10 amorphous ribbons do not show the best performance in mechanical properties, such as micro-hardness value of 231 Hv (2.26 GPa), nano-hardness value is 3.24 GPa (300 Hv) and modulus from nano-indentation of 62.4 GPa, this composition is close to the two prediction compositions of Mg62Cu27Gd11 (the e/a-variant criterion) and Mg67Cu23Gd10 (the binary eutectic clusters criterion). However, among a series of ternary of Mg-Cu-Gd amorphous ribbons, the better overall thermal properties are seen in the Mg54Cu32Gd14 and Mg54Cu31Gd15 amorphous ribbons. In terms of the bulk Mg65Cu25Gd10 amorphous alloys, the 6 mm bulk metallic glass (BMG) rod can be fabricated successfully with minimum porosity. In order to improve the brittle properties of the Mg65Cu25Gd10 BMG rod, there are two methods applied in this study, namely, the intrinsic toughening method by heat treatment and the extrinsic toughening method of adding reinforcements. For the heat treated Mg65Cu25Gd10 BMG rod, both of the one-step and two-steps BMG rods show no distinct plastic deformation in the engineering stress-strain curves, while the micro-hardness and compressive stress are increased from 270 Hv to higher than 300 Hv and from 804 to 830 MPa. But, for the ductile metal-reinforced Mg-based BMG rods, the brittle properties are improved. For the Nb-reinforced Mg65Cu25Gd10 BMG rods, the compressive stress decreases from 804 to 595 MPa and the plastic strain increases from 0 to 0.48% with increasing volume fraction from 0 to 17.3%. But, for Mg65Cu25Gd10 BMG rod reinforced by 21.6% porous Mo, the compressive stress and plastic strain are 821 MPa and 1.63%, respectively. Moreover, for the porous Mo-reinforced Mg58Cu28.5Gd11Ag2.5 BMG rods, the compressive stress increases from 827 to 1111 MPa and the plastic strain increases from 0 to 7.84% with increasing volume fraction from 0 to 25.4%.

The mechanical properties and micro-forming of the Au-based bulk metallic glasses are reported in this thesis. The original ingots were prepared by arc melting and induction melting. The Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glasses with different diameters 2 and 3 mm were successfully fabricated by conventional copper mold casting in an inert atmosphere. By the observation of transmission electron microscopy diffraction pattern, there are crystalline phases among the amorphous matrix phase. The Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glass shows the high glass forming ability and good thermal stability. By the Differential scanning calorimetry (DSC) results, the values of£G£Vx and £G£Vm are 50 and 21 K. And Trg, £^, and £^m values for the Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glass (BMG) at the heating rate of 0.67 K/s are 0.619, 0.430 and 0.774, respectively. The mechanical properties of Au49Ag5.5Pd2.3Cu26.9Si16.3 in terms of compression testing are examined using an Instron 5582 universal testing machine. Room temperature compression tests are conducted on specimens with various strain rates. To know the size effect, the micro-pillars were made by using a focus ion beam (FIB) technique. The micro-pillars were under the tests of compression at different strain rates, compared with macro-scale 2 mm rod specimens. In contrast to the brittle fracture in a bulk sample, these micro-pillar specimens show significant plasticity. The morphology of compressed pillar samples indicates that the number of shear bands increased with the sample size and strain rates.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Food Science." Includes bibliographical references.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 168-174). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis--M. Phil., University of Hong Kong.

Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009. / Committee Chair: Li Mo; Committee Member: Chou Meiyin; Committee Member: First Phillip; Committee Member: Nguyen Toan; Committee Member: Zangwill Andrew. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Not available / text

Understanding the radiolysis of impure water and resulting reactions is crucial to many fields. Reactions driven by low energy electrons (LEE) are of special interest, as high-energy radiation generates large quantities of these electrons, which then provide the energy for most subsequent reactions. Interfacially located reactions are also of particular interest, both as models for heterogeneously distributed reactions occurring during radiolysis, and in their own right, as radiation-driven reactions at interfaces are responsible for key processes such as corrosion and DNA damage. To study LEE-driven reactions at interfaces, thin-layered films of amorphous solid water (ASW) and methanol were grown under ultra-high vacuum conditions using molecular beam techniques. The films were exposed to a beam of low-energy (100eV or less) electrons, and studied using electron-stimulated desorption (ESD) and temperature programmed desorption (TPD). ESD studies indicated that methanol moves through a water film during deposition at 80 K but not at 50 K. This transport was not seen during thermal annealing, but radiation-induced mixing was observed at all temperatures. Major and minor LEE radiation products of pure methanol films were identified and found to be consistent with previous results. Products of LEE irradiated layered methanol/water films were determined for the first time using ESD and TPD spectra, and found to be limited to H₂, O, O₂, CH₂O, C₂H₆, CO, CO₂, CH₃OCH₃, and CH₃CH₂OH. The effect of adding methanol to an ASW film on the production in ASW of H₂ and O₂ was also examined. The interface created by the addition of CH₃OH to ASW was found to generate H₂ in previously non-reactive regions of the water film by increasing water-water and water-methanol reactions. Radiative mixing of CH₃OH and ASW enhanced this effect, presumably by increasing the region of disrupted H-bonding in the ASW. In contrast, the addition of CH₃OH at low coverages suppressed O₂ production in both unprocessed and preprocessed ASW layers. Modeling indicates that methanol scavenging of the O₂ precursor OH and of the reaction-driving electrons is responsible for this reduction in O₂ signal.

published_or_final_version / Physics / Master / Master of Philosophy