The systems studied involve deposition of metals of a larger atomic diameter on a Cu{100} single crystal surface under vacuum and determining the structures formed along with the effect on the Cu{100} substrate. Cu microelectrodes were fabricated and characterised with Indium electrodeposited on the electrode surface. The In on Cu{ 100} growth mode is compared with the growth mode of electrodeposited Indium on Cu microelectrodes. The Cu{100}/In system has been studied for the In coverage range 0.1-0.65 monolayer using Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). The Auger signal versus deposition time plot for the deposition of In on Cu{ 100} is characteristic of the Stranski-Krastanov growth mode. In this deposition mechanism the first atomic layer grows in a layer by layer fashion but when monolayer point is reached, subsequent growth occurs in the form of 3D crystallites. At a concentration of 0.4±0.05 monolayer In forms a ( 9 V 2 x 2 a / 2 )R 4 5 ° on the Cu{100} surface which on heating above a temperature of 373K undergoes a reproducible phase transition to form a c(2x2) phase. Increasing the In deposited to a surface concentration of 0.6±0.05 monolayer results in a Cu{100}-c(4x4)-ln overlayer structure which remains uniform with heating. A Tensor LEED analysis was conducted on this structure in conjunction with K. Pussi et al., from which it was found that the In overlayer consisted of two layers. The In layer closest to bulk comprises a c(2x2) structure with In atoms occupying 4 fold hollow sites with respect to substrate. The top layer is a c(4x4) In layer in which the atoms lie at four fold hollow sites with respect to the c(2 x2 ) layer. The deposition of 0.25ML Sb on clean Cu{ 100} at room temperature results in a p(2x2) LEED pattern which is confirmed by STM. Using Tensor LEED calculations, the structure of the Cu{100}-p(2x2)-Sb phase has been determined. The results show that despite the large size mismatch between Sb (atomic radius = 1.450A) and Cu (atomic radius = 1.278A), a surface alloy is formed in which Sb atoms substitute Cu atoms in the outermost layer. Sb is found to ripple outward from the surface by 0.56+0.05 A. The second and deeper Cu layers are found to be close to their bulk values. As the Sb coverage is increased to a concentration of 0.33ML, the surface exhibits a p(6x6 ) LEED pattern. The atomic resolution STM images for this surface display alternating double and single rows of atoms implying a reconstruction in the selvedge. Based on the STM and LEED results possible models for the Cu{ 100}- p(6 x6 )-Sb structure have been proposed. The favoured structures are based on a slight deformation from the simple c(2 x2 ) surface. Cu microelectrodes were fabricated and characterized using cyclic voltammetry and chronoamperometry. The Cu microelectrodes were found to have a potential window of —0.08 to -0.6V in HCIO4, although this can be improved with pH adjustment, with the potential window found to be at a maximum of +0.1 to -1 .0V at a pH of 4. Chronoamperometric data was taken in differing concentrations of HCIO4 giving resistance, capacitance and RC time constant values for the Cu microelectrode in an HCIO4 electrolyte system. Indium was electrochemically deposited on the Cu microelectrode at a potential of— 0.6V. Cyclic voltammograms are taken at different scan rates to determine the dynamics of In deposition. At low scan rates there was an increase in the amount of. In deposited as witnessed by hysteresis on the cyclic voltammograms. This hysteresis is thought to be caused by In on In deposition. Al scan rates of 1.0Vs"! and above it is thought that little or no In deposition occurs as peaks corresponding to indium reduction or subsequent oxidation are no longer observed. SEM and EDX were used to confirm the deposition of In on the Cu microelectrodes. Chronoamperometric measurements were taken to determine the growth mode and nucleation type of the deposited In. From these measurements, a plot of I/Imax versus t for the. In deposition is compared with nucleation and growth models for 2D progressive, 2D instantaneous, 3D progressive and 3D instantaneous. After comparison it was found that the electrodeposition of In on Cu microelectrodes obeys a progressive nucleation mode with further In growth found to be 3D. This result compares favourably with the growth mode for In deposition on a Cu{ 100} substrate under vacuum, with the growth mode for both being 3D. It was found that the nucleation types for both were remarkably similar with vacuum deposited In and electrodeposited indium both undergoing progressive nucleation.