Lattice damage

The ions not only ate implanted in the surface, but cause considerable lattice damage displacing the host atoms. An amorphous layer maybe formed and the stmcture is not an equiUbtium one. Thus the solubility of the implanted ions may gteady exceed the solubility limit. AH of these effects combine to produce a hard case. 

Much of the microscopic information that has been obtained about defect complexes that include hydrogen has come from IR absorption and Raman techniques. For example, simply assigning a vibrational feature for a hydrogen-shallow impurity complex shows directly that the passivation of the impurity is due to complex formation and not compensation alone, either by a level associated with a possibly isolated H atom or by lattice damage introduced by the hydrogenation process. The vibrational band provides a fingerprint for an H-related complex, which allows its chemical reactions or thermal stability to be studied. Further, the vibrational characteristics provide a benchmark for theory many groups now routinely calculate vibrational frequencies for the structures they have determined. 

Uniaxial stress results have been reported for several of the IR bands associated with H decorated lattice damage (Bech Nielsen et al., 1989). For these experiments H+ was implanted into Si at room temperature. The resulting spectral features correspond to those observed previously by Stein (1975) and others (see Section III.3). Uniaxial stress splitting patterns were measured for infrared absorption spectra taken at 9 K. The... 

Because of the lattice damage, the absorptions due to the local modes of vibration are usually broader in implanted materials than, for instance, in plasma diffused samples. For proton energies around 1 MeV, the line-widths are in the range 5-100 cm-1 (as compared with 0.1-5 cm-1 for plasma hydrogenation). 

The interaction of an electron with a surface produces at least three phenomena which are important in a plasma environment. They are (1) chemical reactions between gas phase species and a surface where electron bombardment is required to activate the process, (2) electron-induced secondary-electron emission, and (3) electron-induced dissociation of sorbed molecules. A fourth phenomenon — lattice damage produced by energetic electrons — depends sensitively upon the properties of the material being bombarded, and, it is important in specialized situations, but it will not be discussed in this paper. 

The process of introducing impurities into silicon is called predeposition. Chemical predeposition is described in terms of a solution to the diffusion equation. Predeposition by ion implantation is described in terms of ion penetration into silicon, distributions of implanted impurities, lattice damage, etc. 

In the case of marine deposition, the transport of particles through the air results in the anneahng by ultraviolet radiation from the Sun. The reset minerals then act as accumulators of lattice damage once they are buried. The technique has been estabhshed for wind-blown deposits such as dunes and loess deposits. Wintle and Huntley (1979) apphed it to deep-sea sediments, building on initial studies by Huntley and Johnson (1976). Subsequently, there has not been a great deal of work on deep-sea sediments, and most of the interest has shifted to sand dunes and loess deposits where the method provides a unique dating tool. 

The remaining studies on oxidation of metals have been performed mainly with the aim of looking into the corrosion properties of materials. Thus, in 1971 it was found that the implantation of boron generated passivation in copper The oxidation rate of zircaloy4 in oxygenated water at 300°C was suppressed by ion bom-bardment Implantation of reactive ions such as O and chemically inactive ones such as Ar and Xe yielded the same retardation of the oxidation, suggesting that the lattice damage was the main reason for this effect. 

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