Temperature effects in thin films of silicon oxide
The use of thin film capacitors as a component in microminiaturized electrical circuits has made it necessary to obtain a more complete understanding of the conduction mechanisms occurring in these films. Silicon oxide was chosen as the dielectric material for study and the temperature behaviour of...
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Imperial College London
1968
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| Online Access: | https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.623094 |
| Summary: | The use of thin film capacitors as a component in microminiaturized electrical circuits has made it necessary to obtain a more complete understanding of the conduction mechanisms occurring in these films. Silicon oxide was chosen as the dielectric material for study and the temperature behaviour of thin film capacitors was investigated in order that films with low temperature ageing and a high stability could be prepared. D.C. and A.C. conduction processes in dielectric films have been examined with particular reference to the amorphous nature of the dielectric materials considered. The theoretical contributions to the temperature coefficient capacitance have been outlined. Apparatus was designed and constructed so that complete metal-dielectric-metal sandwiches could be prepared and measurements performed on them without breaking the vacuum. The effects of deposition conditions and post-deposition heat treatment was investigated and empirical equations were obtained for the reduction in loss and capacitance during the annealing treatment. D.C. results were similar to those obtained by previous workers. A precise interpretation of these results was not possible due to uncertainties in the spatial and energy band structure of the amorphous films. From observation of the decay of the absorption current a low frequency loss peak was predicted. The audio frequency results were influenced by this peak, particularly at high temperatures. Above the audio frequency region both the loss and permittivity were independent of frequency with a very low activation energy (< 0.1 eV) which was probably due to some form of electron hopping conduction. The temperature coefficient of capacitance was found to depend on the loss, particularly for high loss materials. The intrinsic contribution to the temperature coefficient of capacitance was probably due to the temperature dependence of the ionic polarizability. |
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