From electrodeposited indium antimonide to photonic crystals and nanopatterned molecular templates

The present study is based on electrochemically formed compound semiconductor such as InSb with specific applications to thin film, 3-dimensional photonic crystal structures and nanostructure deposition. The applications explore the fabrication from the bottom up by electrodeposition to form 3-D microstructures and 2-D nanostructures.; Stoichiometric InSb was deposited at room temperature from an aqueous citrate electrolyte onto polycrystalline Cu substrates and onto single crystal Si substrates. The stoichiometry of the deposited film was found to depend primarily on the electrolyte composition and less on the applied voltage, pH, and substrate. The crystalline structure of the deposited film was studied by X-ray diffraction, revealing post deposition recrystallization and stress relaxation at room temperature. The intraband absorption coefficient for near-stoichiometric deposition was sufficiently low (400cm-1) to suggest the possibility of the device quality InSb electrodeposition.; A new 3-D photonic crystal with a structure similar to the woodpile, which consists of the standard four layers of semiconductor stripes but with sequential layers of stripes separated by connecting pillars, was introduced. The calculated photonic band gap is 28% for the optimized structure, using the dielectric coefficient of InSb. Two different fabrication procedures were proposed for the modified woodpile structure. The first fabrication strategy is based on sequences of lithographically patterned steps followed by electrodeposition. The second procedure is an anisotropic directional etch of holes at 45° to the wafer normal performed twice through a mask. Optical measurements made on the electrodeposited photonic crystal samples did not demonstrate the photonic band gap formation. The fabricated small numbers of layers, size fluctuation in the structure and resultant large scattering from the electrodeposited photonic crystals strongly modifies the optical properties of the photonic structures.; Direct surface patterning based on self-assembling with large rigid, hexagonal shaped single molecules was demonstrated. Two basic organizational behaviors of the molecules were observed from Scanning Tunneling Microscopy measurements. Molecular resolution images, of lateral organized densely packed patterns and long tubular type structures were recorded and compared with macromolecular models. InSb and Cu nanostructures were electrodeposited into the self-assembled molecular templates. The morphology of these electrodeposited nanostructures was probed and analyzed.