Thermoelectric materials of the Fe-Al binary system were prepared at 423 K by electrodeposition in molten salts of the AlCl3-NaCl-KCl-FeCl2 quaternary system. The effects of the current density at the constant content of FeCl2 were investigated in addition to the FeCl2 content at the constant current density on the compositions and morphologies of the electrodeposited Fe-Al alloy films. When the Fe-Al alloy films were electrodeposited in the 63.59 mol%AlCl3-25.83 mol%NaCl-9.94 mol%KCl-0.64 mol%FeCl2, the constant molar ratio for FeCl2 to AlCl3 was 1:100, the Al contents electrodeposited in the film were increased as a function of the applied current density followed by morphological change to a powder over 150 Am－2, indicating that the current density for smooth film preparation was 100 Am－2. At constant current density of 100 Am－2, the various Al contents in the films were obtained as a function of the FeCl2 content in the molten salt, resulting in the significant increase of Al content below 0.5 mol% FeCl2 in the molten salt. Electromotive force was generated by a temperature difference on the obtained Fe-Al alloy films. The sign of generated electromotive force, the type of thermoelectric conversion, depended on the Fe-Al alloy film composition. These obtained results clarifying the condition of electrolysis to control the composition determining thermoelectric property of the film are expected to be useful to develop thermoelectric devices that use Fe-Al film.
Polyglycolic acid (PGA) used for this study is categorized as a polyester resin comprising hydrogen, carbon, and oxygen. The usage of PGA in electronic parts such as printed circuit boards has an important role in the protection of environment, but several difficulties must be overcome. For this study, an Ar＋ ion beam was used to modify a PGA surface so that the metal-film-coated PGA durability was improved. Then double-layer Cu/Ti films were deposited on the modified PGA using vacuum evaporation. Results showed that the Ti layer between the Cu film and the surface-modified PGA exhibited superior adhesion and electrical conductivity compared to those of a Cu single-layer film. Those properties showed a maximum value at 30 nm Ti thickness, but deteriorated with increasing Ti-layer thickness. Electrical conductivity measurements suggest the possible use of PGA for printed circuit boards.
After zinc oxide (ZnO) thin films were deposited using chemical solution methods such as sol-gel method and metal organic decomposition, the deposited ZnO thin films were used as a precursor promoting adhesion in Cu/glass stack systems. Transparent ZnO thin films were deposited on a borosilicate glass substrate using chemical solution methods. X-ray diffraction and X-ray photoelectron spectroscopy analyses revealed that the deposited ZnO thin films have no specified orientation and much less carbon contamination. The obtained ZnO thin films comprised two characteristic layers: a porous structure formed at the glass substrate side and a dense layer formed at the surface side. The adhesion of Cu/glass stacks formed by the ZnO thin films increased markedly when the ZnO/glass stacks were annealed at 600 ℃. Furthermore, the adhesion increased with increasing ZnO removal time, reaching a maximum value at a certain removal time, but decreasing thereafter. These results indicate that the deposited ZnO thin films are effective for the improvement of Cu/glass stack adhesion. Results show that a Zn-doped layer formed at the glass surface plays an important role in the improvement of Cu/glass stack adhesion.
Amorphous lithium phosphorus oxynitride (LiPON) thin films were deposited on SUS plates from a Li3PO4 target using RF magnetron sputtering with induction gas having various N2 concentrations. The ionic conductivity of the amorphous LiPON films was approximately 7.6×10－6 S･cm－1 at 75% N2 concentration, at which both doubly and triply phosphorus-coordinated nitrogen units would be linked to the Li3PO4 structure.