Vacuum/volume 39/number 1 /page 29/l 989 Printed in Great Britain

0042-207X/89$3.00+.00 Pergamon Press plc

Abstracts

Physical limitations of molecular electronic devices

M Marvan, Faculty of Mathematics and Physics, Charles Univer- sity, Prague, Czechoslovakia

Logical and memory elements working on the molecular level have been proposed recently. There are theories concerning the realization of the information transfer between such elements. According to the latest opinion of the physicists, molecular elec- tronics is not in contradiction with the principal physical laws. In our opinion, the possible existence of a chip with high density of elements, extreme reliability and large speed of operation is still open.

This problem is solved by the means of quantum mechanical models. Great attention is devoted to the quantity of energy dissipation. The relation between the density of logical elements on a chip, operation rate and reliability is found.

The modification of polymer surfaces by the deposition of thln films

R P Howson, A G Spencer, K Suzuki and R lkwin, Loughborough University of Technology, Loughborough, Leicestershire LEll 3TU, UK and I Sutherland, Loughborough Consultants Limited, Loughborough University of Technology, Loughborough, Leicestershire LEll 3TU, UK

Techniques for depositing thin films onto polymers are now being developed which result in extremely good adhesion. They allow the formation of hard, abrasion resistant, inorganic materials on the surface of the polymer, but in the process they modify its surface. The process that has been investigated and is reported here is that of reactive dc planar magnetron sputtering of oxides onto high quality optically clear sheet polymers with and without surface preparation in a plasma provided by an rf discharge. The

film-substrate interface has been investigated using depth profiling XPS analysis.

It is demonstrated that exposure to a low pressure plasma containing oxygen can result in oxygen being removed from the polymer and the interface adhesion is provided by a non-oxygen chemical bond. Physical modification of the surface of the poly- mer can also be observed. It has been observed that the high ion energy available in low pressure discharges can lead to surface changes which are quite different from those encountered in discharges at higher pressures. This results in an adhesive bond between film and substrate which offers much promise for simple modification of the properties of a polymer surface.

Polymer and carbon films deposited by dc planar magnetron

H Biederman, Department of Polymer Physics, Charles University, V HoleSoviEkach 2, 180 00 Praha 8, Czechoslovakia and R P Howson, Department of Physics, Loughborough University of Technology, Leicestershire LEll3TU, UK

Discharges operated in hydrocarbon gases and excited from rf and dc power supplies have been used for production of carbon films. Especially hard carbon films (a-C : H, DLC) have been prepared in rf discharge when the substrate rested on the capaci- tively coupled electrode which developed negative self bias poten- tial attracting an energetic positive ion bombardment. Recently encouraging reports have been published on a dc unbalanced planar magnetron which has been used for sputtering of graphite in argon/hydrocarbon gas mixtures.

We have prepared films using the above mentioned arrange- ment and argon/propane mixtures. The optical (transmission) and electrical properties of the films have been determined. The optical gap obtained increased from 0.8 eV to more than 2 eV as the amount of propane in the mixture increased from zero. The structures of the films have been determined from IR spectra. Finally the incorporation of several metals (e.g. Ag, MO, Pt) has been performed and basic film properties studied.

29