Hewlett-Packard Development Company, L.P. (Houston, TX) has developed electrophotographic techniques that allow for ease of design changes and quick process turnaround times for implementing different nano-scale device configurations to be printed using nanowires of differing compositions.
The electrophotographic systems can be used to produce a wide variety of electronic devices. Although no particular limitation on the potential applications. H-P electrophotographic systems can be used to produce devices such as transistors, metal semiconductor field effect transistors (MESFETs), metal oxide field effect transistors (MOSFETs), junction field effect transistors (JFETs), radio frequency identification tags (RFIDs), memory, battery cells, solar cells, light emitting diodes (LEDs), CPUs, large area display panels (e.g. TFTs), and sensor arrays
Additionally, say inventors Amir A. Yasseri, Theodore I Kamins and Shashank Sharma many of the basic components for electrophotographic printing are readily available and can be incorporated to take advantage of available equipment to increase print speeds and reliability.
According to the nanowire fabrication process described in U.S. Patent 7,638,431, a metal is deposited onto a surface electrochemically using a deposition solution including a metal salt. In making a composite nanostructure, the solution further includes an enhancer that promotes electrochemical deposition of the metal on the nanostructure. In a method of forming catalyzing nanoparticles, the metal preferentially deposits on a selected location of a surface that is exposed through a mask layer instead of on unexposed surfaces.
Silicon (Si), germanium (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium indium arsenide (GalnAs) and zinc oxide (ZnO), are a few non-limitative examples of the materials that are useful as a nanowire material. Carbon nanotubes may also be used.
The method of making nanowires also comprises enhancing a deposition solution that comprises a metal salt; and electrochemically depositing a metal from the enhanced deposition solution onto a nanostructure. Enhancing a deposition solution comprises introducing an enhancer to the deposition solution. The enhancer promotes electrochemical deposition of the metal onto the nanostructure.
A composite nanostructure apparatus includes an array of nanowires and the metal deposited on at least some nanowire surfaces. Some of the nanowires are heterogeneous, branched and include different adjacent axial segments with controlled axial lengths. In some deposition solutions, the enhancer controls oxide formation on the surface and causes metal nanocrystal formation. The deposition solution further includes a solvent that carries the metal salt and the enhancer.
Current electrophotographic techniques which can be used in connection with the H-P system allow for features having a smallest dimension of about 10 .mu.m, and typically from about 50 .mu.m. In addition, no electrodes are required for placement of particles. Similarly, the system does not involve electret materials or PDMS stamps to transfer charge.
Electret is a dielectric material that has a quasi-permanent electric charge or dipole polarization. An electret generates internal and external electric fields, and is the electrostatic equivalent of a permanent magnet.
Regardless of the specific device design, the H-P methods can be useful in producing electrical devices which have at least one device layer for performing an electrical function. These device layers which form the device precursor can be formed with electrophotographic steps. The resulting devices can have unique properties such as flexibility and high reliability.
Regardless of the specific device design, the H-P methods can be useful in producing electrical devices which have at least one device layer for performing an electrical function. These device layers which form the device precursor can be formed with electrophotographic steps. The resulting devices can have unique properties such as flexibility and high reliability.
Further, the consolidated anisometric particulate materials tend to provide improved contact between particles which can improve reliability, service life, and maximize current. Typically, such devices can be then incorporated into a commercial product such as a multi-component device and then applying a voltage to the electrical device to achieve a designed functionality.
