Implanted layers layer preparation

There are, however, continuing difficulties for catalytic appHcations of ion implantation. One is possible corrosion of the substrate of the implanted or sputtered active layer this is the main factor in the long-term stabiHty of the catalyst. Ion implanted metals may be buried below the surface layer of the substrate and hence show no activity. Preparation of catalysts with high surface areas present problems for ion beam techniques. Although it is apparent that ion implantation is not suitable for the production of catalysts in a porous form, the results indicate its strong potential for the production and study of catalytic surfaces that caimot be fabricated by more conventional methods. 

The release of steroids such as progesterone from films of PCL and its copolymers with lactic acid has been shown to be rapid (Fig. 10) and to exhibit the expected (time)l/2 kinetics when corrected for the contribution of an aqueous boundary layer (68). The kinetics were consistent with phase separation of the steroid in the polymer and a Fickian diffusion process. The release rates, reflecting the permeability coefficient, depended on the method of film preparation and were greater with compression molded films than solution cast films. In vivo release rates from films implanted in rabbits was very rapid, being essentially identical to the rate of excretion of a bolus injection of progesterone, i. e., the rate of excretion rather than the rate of release from the polymer was rate determining. 

The surface of a solid sample interacts with its environment and can be changed, for instance by oxidation or due to corrosion, but surface changes can occur due to ion implantation, deposition of thick or thin films or epitaxially grown layers.91 There has been a tremendous growth in the application of surface analytical methods in the last decades. Powerful surface analysis procedures are required for the characterization of surface changes, of contamination of sample surfaces, characterization of layers and layered systems, grain boundaries, interfaces and diffusion processes, but also for process control and optimization of several film preparation procedures. 

Fig. 19 Histological preparation (haematoxylin and eosin staining) of square sections, a BASYC in the middle region of the interposition four weeks after implantation in the carotid artery of the rat, b untreated carotid artery of the rat. - endothelial cell layer. BASYC layer...

A few articles related to the bombardment of Si suboxide layers with SHI have been published earlier. However, the processes in SHI tracks are not fully understood. In our study we have used SiOz layers implanted with Si ions to the excess Si concentrations, optimal for preparation of light-emitting Si-ncs. 

In the case ofbf/N2 implantation into Si, the buried insulating SisN4 layer is formed in Si N. The structure of SOI-like structures prepared by annealing of Si N, similarly as in the case of Si 0, depends on HP exerted by ambient gas during processing [4-6]. However, due to still unsolved problems (e.g. 

XTEM images of the Si N samples allow to estimate the thickness (/) of the top Si and buried SiN insulating layers. For the sample SI, the thickness of the top Si layer equals to about 150 nm both in the case of processing under 10 Pa and 1.1 GPa. In the case of processing for 5 h at 1400 K under AP, the thickness of buried SiN layer is equal to about 45 nm, whereas to about 60 nm after the treatment under 1.1 GPa. For higher implanted dose, the thicknesses of the top Si layer (60 nm) and the buried nitride (205 nm) are almost the same in the structures prepared by annealing under AP and HP. 

The HP treatment of Si N prepared by nitrogen implantation with dose, D > 1X1 o cm, produces continuous buried insulating nitrogen-enriched layer. 

Samples for this study were prepared on phosphorus-doped epi-Si (p 30 Q cm) grown on highly Sb-doped (p 0.01 Q cm) bulk Czochralski-grown Si wafers. The thickness of the epi layer was about 45 pm. The oxygen concentration in the samples studied was close to 4x10 cm The p -n junctions were formed by the implantation of boron ions with subsequent annealing at 1470 K in nitrogen ambient. 

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