Deposition films, parameters

Figure 1.17 Electrochemical phase diagram showing the composition of co-deposited films. Parameter a is the flux ratio of Se(IV) and CU(II) ionic species to the surface. MSE...

Many of the qualitative adhesion tests vary with plate thickness. As indicated above, adhesion is better for thinner deposits. That, it was stated, has to do with the stress present in deposited films. A specified plating thickness should therefore be a given parameter requirement for adhesion testing. 

As is the case for the dark resistivity, the dependence of the sensitivity of the photoconductivity (defmed here as the ratio between light and dark conductivity) on the deposition parameters is far from clear-cut. Some observations can be made, however. The first (obvious) one is that for a high sensitivity, the dark resistivity must be high. Apart from this, there does seem to be a general trend (clear-cut in the triethanolamine and citrate baths and seen also by the lack of appreciable photoconductivity in the one low- (room-) temperature-deposited film reported [40]) of an increase in photosensitivity (due to decrease in light resistivity) with increasing deposition temperature. 

From solutions of Bi and Pb nitrates, complexed with triethanolamine and ammonia, mixed sulphides were deposited with thiourea on glass at pH values between 9.5 and 11 and at 100°C (initially) followed by slow cooling in the solution [35]. Elemental analyses showed the presence of both metals in the films. It is not clear whether solid solution formation occurred in the as-deposited films, although the lattice parameters did vary non-monotonicaUy, depending on composition. 

For the chemical vapor deposition of ZnO, the ratio of the various precursors that participate in the chemical reaction leading to ZnO formation is an important parameter it influences the stoichiometry of the deposited films and therefore, also, their properties. DEZ and DMZ, which are the metal-organic precursors mostly used for ZnO formation, react in the presence of oxidizing agents like O2 or H2O. The equation for the complete oxidation reaction of DEZ as well as the equation for the complete reaction of DEZ with H2O are given here as examples ((6.5) and (6.6)) ... 

The typical parameters for the PLD of epitaxial ZnO-based thin films on sapphire including information about target preparation are listed in Table 7.3. Within the range of these software controlled parameters, the properties of the deposited films differ widely, as will be shown in Sect. 7.4. Beside the parameters listed in Table 7.3, the film properties will be influenced furthermore by a few more internal effects, which will be listed and discussed in the following according to the scheme effect/problem-cause-solution. Only the careful consideration of all these hidden effects by experienced operators can ensure the highest quality and reproducibility of PLD grown films. 

For the sake of this discussion, it is assumed that the deposit is electrically insulating. This limits the available anodic and cathodic sites to the material surface at the base of the pores. If it is assumed that steady-state conditions exist within the deposit, then the only film parameter that changes as corrosion progresses will be its thickness. Ideally, the deposit can be considered to contain a uniform distribution of cylindrical pores, each of radius r, and length l with the latter equivalent to the thickness of the film. The cross-sectional area of the pores will be Jjriri, their volume YjirU, and the total volume of the deposit including pores, IA. 

The post deposition processing parameters (curing temperature, time) have a profound impact on the thermal properties of polyimide thin films. It has been observed that, films cured at around 300°C for 1 hour exhibit markedly superior thermal stability as compared to those that were not cured." ° Cured PMDA-ODA... 

For the aquisltion of vanadium dioxide thin films one needs to solve such a problem that together with the growth of VO2, additional compounds as V2O3, V3O5, V2O5 can be formed. Therefore a precise control of deposition process parameters is required. 

The morphology and the chemical composition of the deposited film were analyzed by SEM and EDX. Results showed that the ratio of acetylene to oxygen is an important parameter in determining the growth rate and the quality on the structure of carbon deposited films. 

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