The electrodeposition of WO3 thin films from peroxy-tungstate solution is discussed. The emphasis is on the feasibility of this deposition technique for production of electrochromic devices. Therefore, the influence of deposition parameters (solution composition, electrodeposition potential, mass transport, etc.) on the properties of WO3 was studied. Furthermore, it was investigated whether electrodeposition of WO3 offers unique possibilities as compared to WO3 deposition by other techniques.

The influence of film/electrolyte interface on structure and electrochromic properties of amorphous WO3 (a-WO3) films has been studied using cyclic voltammetry, optical electrochemistry and vibrational spectroscopy.

A LaMnO3 precursor was electrolessly deposited on a YSZ substrate in a solution containing Mn2+, La3+, an oxidizing agent and some additives. Peroxydisulfate was used as the oxidizing agent. The LaMnO3 precursor was an amorphous and hydrous MnO2 which contained La3+ ions. The incorporation of La3+ ions into the precursor oxide film was based on the ion-exchange reaction, where La3+ ions in the solution were exchanged for H+ ions on the deposited amorphous and hydrous MnO2. A La1-xSrxMnO3 precursor was also prepared from the LaMnO3 precursor by the ion-exchange reaction of some of the La3+ ions in the LaMnO3 precursor for Sr2+ ions in the solution. (La0.5Sr0.5)0.75MnO3 perovskite film was obtained from the precursor films on Pt substrate by heat-treatment at 800 °C.

Described are results showing that an oscillating flow-field can induce spatially periodic composition variations in electrodeposited NiFe films. Flow-induced NiFe composition modulated alloys (CMA's) were deposited on the disk of a rotating disk electrode by oscillating the disk rotation rate during galvanostatic plating. Deposit composition and structure were investigated using potentiostatic stripping voltammetry and scanning probe microscopy. Results illustrate a linear relationship between the composition modulation wavelength and the flow oscillation period. CMA's with wavelengths less than 10 nm can be fabricated when plating with a disk rotation rate oscillation period less than 3 seconds.

Electrodeposited magnetic multilayer films consisting of alternating layers of a ferromagnetic and a non-magnetic metal may exhibit giant magnetoresistance (GMR), but the effect is very sensitive to whether deposition is carried out under potentiostatic or galvanostatic control, and the choice of substrate. The texture of Co-Ni-Cu/Cu superlattices grown on polycrystalline (100)-textured Cu plates and (HO)-textured Cu foil under potentiostatic control depended on that of the substrate, while comparable superlattices grown under galvanostatic control had a predominantly (111) texture. The films grown under galvanostatic control generally exhibit AMR or smaller GMR. The magnetic and magnetotransport properties of Co-Ni-Cu/Cu superlattices and a single-layer Co-Ni-Cu film electrodeposited directly onto n-GaAs (100) are also described, and evidence is presented for an in-plane magnetic anisotropy in these samples.

Metallic nanowires are synthesized by electrochemical growth in nanopores of either track-etched polycarbonate membranes or anodized aluminum films. The potentiostatic growth is systematically investigated for track-etched membranes with nominal pore diameters dN between 10 and 80 nm. For this model system, the cross-section of the metallic wires is found to vary: the wire diameter, which is argued to directly reflect the pore diameter, is observed to be substantially larger in the middle than at both ends. Therefore, the pores are not cylindrical with constant cross-section, but appear to be ‘cigar-like’. Inside the membranes, the pores are wider by up to a factor 3.

The aluminum oxide template has successfully been used to prepare a colloidal suspension of gold needles (anisotropie metallic colloid) by growing Au wires in the pores, dissolving the aluminum oxide and finally stabilizing and dispersing the ‘nano-rods’ in water. Visible near-infrared absorption spectroscopy reveal two absorption maxima caused by the anisotropy of these scatterers. The maxima can be assigned to a longitudional and transversal plasma resonance.

Anodic aluminum oxide (AAO) may be used as a template for electrochemically fabricating metal and semiconductor nano-wires. We assess the seminal factors involved in each step in this fabrication process with an aim at producing device-quality semiconductor nano-arrays. This includes an analysis of the electrochemical factors, the structural effects resulting from the templating, the crystallinity of the nano-wires, their anisotropy and their suitability for device applications.

Nanowires, 100 nm in diameter and 6 μm in length, with an oxide barrier intercalated between two ferromagnets, were produced via an electrochemical route. Non ohrnie behavior wa found. The magnetoresistance of Ni/NiO/Co heterostructures abruptly change by more than 7% at the switching field of the ferromagnets.

Sonoelectrochemistry, or pulsed electrodeposition at high current density in presence of high intensity ultrasound, is used to produce magnetic powders with a mean diameter in the range of 100 nm. Pure iron, cobalt and nickel powders are produced together with their binary and ternary alloys. The powders are crystalline and homogeneous as observed by scanning and transmission electron microscopy, electron diffraction and X-ray fluorescence. The compositions of the binary and ternary alloy powders reproduce strictly the iron, nickel and cobalt compositions of the starting electrolytes except for the nickel-cobalt alloys.

Electrodeposition through photoresist masks is a critical, enabling technology for fabrication of the thick structures (of up to several hundred microns) involved in HI-MEMS. Process integration is an important issue in HI-MEMS. The electrodeposited structure is influenced by the choice of optical or X-ray lithography. Thickness uniformity of the deposit on the wafer scale can be optimized by the use of an auxiliary cathode. On the device or feature scales, thickness uniformity can be improved by the thoughtful design of the pattern to be plated.

A variable reluctance, planar, integrated mini-motor with a 6 mm diameter rotor has been fabricated using lithography, electrodeposition and dielectric planarization processes. The rotors were fabricated separately, released from the substrate, and slipped on the shaft, which was plated up as part of the stator fabrication.

Thin-films of YBa2Cu3O7 (YBCO) superconductor precursor were synthesized using an electrodeposition process. The YBCO precursor thin films were deposited on Ag foils using pulsed potential deposition conditions of 10 s at - 4 V and 10 s at -1 V (versus Ag reference electrode). The post-annealed films showed zero electrical resistance at 60 K. The procedures for the fabrication of a high precision micro-sensor using YBCO superconductor for measurement of weak magnetic fields are outlined. The micro-sensor templates were patterned using X-rays and precursor films were deposited into the features.

The electrodeposition of Co/Pt multilayers have been carried out under potential control. The influence of the deposition polential on the structure of the multilayers is investigated. Deposition of the Pt layers at an electrode potential in the Co dissolution region gives rise to the destruction of the compositionally modulated structure and a large internal stress. The structure and magnetic properties of electrodeposited Co/Pt multilayers are discussed in connection with the dissolution of Co during Pt deposition

A variety of Cu/(Ni, Co) multilayers have been grown on Cu single crystals by pulse plating from an alloy electroplating bath. Copper is deposited under mass transport control while the iron group metal is deposited under interfacial charge transfer control. The structural evolution of these films is influenced by the morphological instability of the mass transport limited copper deposition reaction and the development of growth twins during iron-group metal deposition. Specular films have been obtained for growth on Cu(100) while rough, defective films were typically obtained for growth on Cu(111) and Cu(110).

Fibonacci Ni/Cu multilayers were fabricated by electrodeposition for the first time. The deposition of these quasiperiodic as well as periodic multilayers was fully controlled by a computer. X-ray diffraction spectra from a quasiperiodic multilayer built up from blocks of Ni(8ML)/Cu(4.5ML) and Ni(8ML)/Cu(9ML) indicate that the multilayer is of good quality. Since a Fibonacci multilayer has a quasiperiodic nature, the magnetoresistance effect in this system is expected to give more information about the mechanism for magnetic interlayer coupling in the GMR effect. The magnetic and magnetoresistive properties of the quasiperiodic multilayer were compared with those of two periodic multilayers having the equivalent layer thicknesses as the blocks composing the quasiperiodic multilayer. The magnetic and electrical properties of the quasiperiodic multilayer are not the weighted average of the two periodic multilayers.

Multilayer polymer film electrodes were prepared from the electrochemically synthesized conducting polymers poly(paraphenylene), PPP, poly(3-octylthiophene), POT and from the electrochemically synthesized copolymer of PPP and PO.T. The electrochemical behavior of the multilayer film electrodes made from PPP and POT is compared with the response of a copolymer layer. The structure of the copolymer film could be changed by varying the polymerization potential and the concentration as well as the ratio of the concentration of the two starting materials. Due to the slightly lower (0.15 V) oxidation potential of the POT monomer in comparison to the oxidation potential of biphenyl, POT is usually present to a higher extent than PPP in the electrochemically produced copolymer. The copolymer electrodes, the single polymer film layers and the multilayer polymer film electrodes showed different electrochemical response of the charging-discharging cycle.

The polycrystalline electrodeposits of metals and alloys are characterized by exceptionally fine, equiaxed grain structure; the grain sizes two to four orders of magnitude smaller than those encountered in the bulk metals are generally obtained. Under the conditions of high cation discharge rate, twins accommodate interface growth; elongated grains and columnar morphology then become the common features. The dislocation density can be very high; the dislocations reside primarily as complex substructural configurations which are inherently unstable to thermal or mechanical stimuli. Vacancies, microvoids and vacancy/impurity complexes are endemic to deposits. The defect structure infrastructure (dislocation density and configuration, twinning frequency and hydrogen bubbles) is controlled by the deposition overpotential which also determines the preferred crystallographic texture. When the texture axis is parallel to the twin plane, anisotropie grain structure and columnar morphology are promoted; when the texture axis is perpendicular to the twin plane, a layered structure forms. The textured electrodeposit generates a duplex grain and subgrain structure. The random grains are small and defect saturated; the oriented grains are much larger and relatively free from crystal defects. The incidence of random grains, their size and defect concentration also depend upon the melting temperature of the metal.

Zn-Fe alloys, composed of η (h.c.p.) phase, were electrolytically deposited on cold rolled steel substrates from sulfate electrolytes. Deposits, which initially exhibited a morphology of approximately 20 nm thick platelets inclined 10–20 deg to the substrate surface, subsequently evolved either into triangular pyramids or hexagonal columnar crystals depending on the deposition conditions. A combination of X-ray texture measurements and AFM topographical analysis was used to characterize the growth surface of Zn-Fe alloys. For the morphology of hexagonal columnar crystals, the (00·1) basal planes were aligned perpendicular to the growth direction. For the morphology of the triangular pyramids, the (10·0) and (00·1) planes of η phase were tilted to the growth direction and surrounded the growth surface. For both morphologies the micro- and nanosize steps of growth were identified.

We studied the nucleation of Cu deposited by an electroless bath. A Pd seed layer was sputtered onto a (100) Si substrate and analyzed with GIX, STM, and AFM. The seed layer was then placed in varying ED-Cu bath conditions and also analyzed using GIX, STM, and AFM. GIX analysis results show a (111) texture for the Pd seed layer as well as the ED-Cu layer. The seed layer's influence on the deposited Cu grain's texture was found to be inconclusive.

The production of amorphous electroless nickel (EN) deposits from hypophosphite (H2PO2−) containing solutions is well known. The crystallization of the deposits has been studied by differential scanning calorimetry (DSC) and the changes in crystallization behavior with deposit thickness have been attributed to chemical effects. In this work, DSC results from deposits initiated by use of a noble metal catalyst are compared to those from a conventional zincate.

The implication of the DSC data is that the bulk structure of the EN deposit is determined to a large degree by the mechanism of deposit initiation. This is in contrast to the conventional view that solution chemistry is the dominant factor that determines the properties of the deposit.

A fully encapsulated copper interconnect with CoWP barrier and protection layer can be produced by conformai electroless CoWP barrier layer deposition at the bottom and on the sidewalls of trenches and selective electroless CoWP deposition on in-laid Cu lines. The electroless CoWP deposition is an autocatalytic reaction with activation energy of about 0.985 eV. Deposition rate of about 10 nm/min at 80°C and average surface roughness of 5 nm for 200 nm thick films were measured. CoWP layer with resistivity of 25 μOhms·cm was obtained. Resistivity of electroless CoWP films was decreased from 25 μOhms·cm to 20 μOhms·cm after annealing in vacuum with 10−7 torr at 400°C for 30 min. The RBS spectra of the Cu/CoWP/Co/Si structure formed by electroless CoWP barrier and Cu deposition and annealed at 400°C for 60 min in vacuum 10−7torr showed no interdiffusion in deposited films.