Kurtis Leschkies

Facile synthesis of bimetallic Ag/Ni core/sheath nanowires and their magnetic and electrical properties.

This paper describes a facile method for coating Ag nanowires with uniform, ferromagnetic sheaths made of polycrystalline Ni. A typical sample of these core/sheath nanowires had a saturation magnetization around 33 emu g(-1). We also demonstrated the use of this magnetic property to align the nanowires by simply placing a suspension of the nanowires on a substrate in a magnetic field and allowing the solvent to evaporate. The electrical conductivity of these core/sheath nanowires (2 × 10(3) S cm(-1)) was two orders of magnitude lower than that of bulk Ag (6.3 × 10(5) S cm(-1)) and Ni (1.4 × 10(5) S cm(-1)). This is likely caused by the transfer of electrons from the Ag core to the Ni sheath due to the difference in work function between the two metals. The electrons are expected to experience an increased resistance due to spin-dependent scattering caused by the randomized magnetic domains in the polycrystalline, ferromagnetic Ni sheath. Studies on the structural changes to the Ni coating over time under different storage conditions show that storage of the nanowires on a substrate under ambient conditions leads to very little Ni oxidation after 6 months. These Ag/Ni core/sheath nanowires show promise in areas such as electronics, spintronics, and displays.

Novel Texture Etch Chemistry for Transparent Conducting Oxides Used in Photovoltaic Cells

In thin film photovoltaic silicon stacks, the sun facing contact needs to be transparent and textured. Typically transparent metal oxides are used for this purpose. When using sputtered ZnO as the transparent conducting contact typically an acid etch is used to texture etch the surface. This texturing enables light trapping in the cell and greatly enhances the photoresponse. Traditionally dilute HCl has been used for this purpose. In this paper we present the work on a novel etchant for this purpose consisting of HNO3 and Acetic Acid. This greatly enhances the texturing and hence the light trapping in the cell.