Fabrication and characteristics of highly [Formula: see text]-oriented nanotwinned Au films.

Fine grained and nanotwinned Au has many excellent properties and is widely used in electronic devices. We have fabricated [Formula: see text] preferred-oriented Au thin films by DC plating at 5 mA/cm. Microstructure analysis of the films show a unique fine grain structure with a twin formation.

Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu.

Direct Cu-to-Cu bonding was achieved at temperatures of 150-250 °C using a compressive stress of 100 psi (0.69 MPa) held for 10-60 min at 10(-3) torr. The key controlling parameter for direct bonding is rapid surface diffusion on (111) surface of Cu.

Effect of grain orientations of Cu seed layers on the growth of <111>-oriented nanotwinned Cu.

We investigate the growth of Cu films on two different Cu seed layers: one with regular <111>-oriented grains and the other with very strong <111>-preferred orientation. It is found that densely-packed nanotwinned Cu (nt-Cu) can be grown by pulsed electroplating on the strong <111>-oriented Cu seed layer without a randomly-oriented transition layer between the nt-Cu and the Cu seed layer. The electroplated nt-Cu grow almost epitaxially on the seed layer and formed <111>-oriented columnar structures.

Effect of geometric nanostructures on the absorption edges of 1-D and 2-D TiO₂ fabricated by atomic layer deposition.

2-Dimensional (2-D) TiO2 thin films and 1-dimensional (1-D) TiO2 nanotube arrays were fabricated on Si and quartz substrates using atomic layer deposition (ALD) with an anodic aluminum oxide (AAO) template at 400 °C. The film thickness and the tube wall thickness can be precisely controlled using the ALD approach. The intensities of the absorption spectra were enhanced by an increase in the thickness of the TiO2 thin film and tube walls.

Unidirectional growth of microbumps on (111)-oriented and nanotwinned copper.

Highly oriented [111] Cu grains with densely packed nanotwins have been fabricated by direct-current electroplating with a high stirring rate. The [111]-oriented and nanotwinned Cu (nt-Cu) allow for the unidirectional growth of Cu(6)Sn(5) intermetallics in the microbumps of three-dimensional integrated-circuit packaging; a uniform microstructure in a large number of microbumps of controlled orientation can be obtained. The high-density twin boundaries in the nt-Cu serve as vacancy sinks during the solid-state reaction between Pb-free solder and Cu and greatly reduce the formation of Kirkendall (or Frenkel) voids.

The heterojunction effects of TiO2 nanotubes fabricated by atomic layer deposition on photocarrier transportation direction.

The heterojunction effects of TiO2 nanotubes on photoconductive characteristics were investigated. For ITO/TiO2/Si diodes, the photocurrent is controlled either by the TiO2/Si heterojunction (p-n junction) or the ITO-TiO2 heterojunction (Schottky contact). In the short circuit (approximately 0 V) condition, the TiO2-Si heterojunction dominates the photocarrier transportation direction due to its larger space-charge region and potential gradient.

Direct probe of heterojunction effects upon photoconductive properties of TiO2 nanotubes fabricated by atomic layer deposition.

This study investigated Schottky- and ohmic-contact effects upon the photoresponses of ITO/TiO(2)/Si and Ti/TiO(2)/Si nanotube-based photodiodes. The TiO(2) tube arrays were fabricated by atomic layer deposition (ALD) and shaped by an anodic aluminum oxide (AAO) template on a p-type Si substrate. The contact area between the electrode (Ti or ITO) and the TiO(2)'s tip was varied by tuning the tube's inner wall thickness with ALD, providing a direct and systematic probe of the heterojunction effects upon the photodiodes' responses.

Superparamagnetic and ferromagnetic Ni nanorod arrays fabricated on Si substrates using electroless deposition.

The microstructures and magnetic properties of nickel nanorods fabricated using an anodic alumina oxide template and electroless deposition were investigated. The as-deposited nanorods were found to contain nanocrystalline grains with an average size of approximately 2-3 nm. The temperature-dependent magnetic hysteresis curves indicated superparamagnetic behavior of the as-deposited rods as a result of the reduction of ferromagnetic crystallites.