WA 8 t O dt 4. PEMORMIWA ORGAWIATION REPORT NUMIER(S) S. MONITORING ORGANIZATION REPORT h4UMIER(SiP go MAWE OF PERFOR1miNG ORGANIZATION 60 OFFICE SYMIOL 7& IIINE OF MONITORING ORGANIZATION 2we htgert of the Of appicable) 1) OttPsdn dnsttv Wwivrsit of California 2) OMR AlexandriA' Technical G. ADDRESS "O~. &iM. W4d t co*) 7b. A5010*Csft; Strv. u'W 10 Coe)

Thin films that are grown by the process of sputtering are, by and large, quite unlike the smooth, featureless structures that one might expect. In general, these films have a complicated surface morphology and an extended network of grooves and voids in their interiors. Such features can have a profound effect on the physical properties of a thin film. The surface irregularities and the bulk defects are the result of a growth instability due to competitive shadowing, an effect that also plays a role in geological processes such as erosion. For amorphous thin films, the shadow instability can be described by a remarkably simple model, which can be shown to reproduce many important observed characteristics of thin film morphology.

The electron dynamics for electron energies up to 5 eV has been studied by soft x-ray photoemission spectroscopy. Monte Carlo simulations have been performed to derive the energy dependence of the pair-production rate using these results in combination with published data on the ionization coefficient and on the quantum yield for pair production. The obtained ionization rate shows a very soft threshold at 1.2 eV, approaching the results by Kane [Phys. Rev. 159, 624 (1967)] at higher energies. Several published models have been found to be inconsistent with the full set of experimental data we have considered.

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