Multilayer oxide growth

Burke LD, ODwyer KJ (1992) Multilayer oxide growth on Pt under potential cycling conditions. Electrochim Acta 37 43-50... 

Burke and coworkers [241] have studied the multilayer oxide films grown on silver in base during repetitive potential cycling. It was shown, on the basis of its reduction behavior, that the type of oxide obtained was dependent on the lower limit of the oxide growth cycles. Using limits of 1.03-2.60 V (SHE) the oxide film was assumed to be predominantly Ag20, while at limits 0.7-2.60 V, oxide deposit was assumed to be AgOH. Both types of silver oxides are assumed to be involved in premolecular oxidation and electrocatalysis at silver in base. 

Thus far, our development has been for any inner layer i of the multilayer oxide. It is now required to examine separately the growth of the two layers Lx and LN which are in contact, respectively, with the parent metal and the gaseous oxygen. The growth of Lx proceeds in exactly the... 

Fig. 4 shows a simple phase diagram for a metal (1) covered with a passivating oxide layer (2) contacting the electrolyte (3) with the reactions at the interfaces and the transfer processes across the film. This model is oversimplified. Most passive layers have a multilayer structure, but usually at least one of these partial layers has barrier character for the transfer of cations and anions. Three main reactions have to be distinguished. The corrosion in the passive state involves the transfer of cations from the metal to the oxide, across the oxide and to the electrolyte (reaction 1). It is a matter of a detailed kinetic investigation as to which part of this sequence of reactions is the rate-determining step. The transfer of O2 or OH- from the electrolyte to the film corresponds to film growth or film dissolution if it occurs in the opposite direction (reaction 2). These anions will combine with cations to new oxide at the metal/oxide and the oxide/electrolyte interface. Finally, one has to discuss electron transfer across the layer which is involved especially when cathodic redox processes have to occur to compensate the anodic metal dissolution and film formation (reaction 3). In addition, one has to discuss the formation of complexes of cations at the surface of the passive layer, which may increase their transfer into the electrolyte and thus the corrosion current density (reaction 4). The scheme of Fig. 4 explains the interaction of the partial electrode processes that are linked to each other by the elec-... 

Baseline spectra were taken on 5 NOSA resonators and parallel silicon wafers after surface functionalization. A film thickness of 3.11 nm corresponds to the molecular thickness of native oxide, amine-terminated silane monolayer, and glutaraldehyde functionalization, each of which contributes 1 mn to total film thickness. Since the field at the sensor surface exhibits an exponential decay, the growth of the pofyelectrol5fte multilayer and the resulting effect on resonance shift were fit to an exponential model as shown in Fig. 2. 

The development of film growth processes for large scale multilayer HTS device technologies is crucially dependent not only upon the ability to fabricate large area HTS metal oxide films, but also on the ability to reliably grow HTS lattice-matched, CTE-matched, chemically compatible, low E/tan d metal oxides for use as dielectrics, buffers, substrates, interlayers, and overlayers [282]. (See Fig. 2-11 for an illustration of a complex HTS device). MOCVD processes appear to offer advantages that could be employed to this end, provided that reliable routes to dielectric films can be established. Films of many of the aforementioned lattice-matched metal oxide substrate and/or interlayer materials (Table 2-3) have been grown by MOCVD (see below). 

Si(lOO) with native oxide RT 0.001 nm/s 2 X 10 mbar 5 X 10 mbar two layers three and more perpendicular, closed layers perpendicular, multilayer growth SFM... 

---