Phase transformation in tetrahedral amorphous carbon by focused ion beam irradiation

• Main Author: Philipp, Peter
• Other Authors: Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften
• Format: Doctoral Thesis
• Language: English
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2014
• Subjects: tetraedrisch amorpher Kohlenstoff; fokussierter Ionenstrahl; Phasentransformation; Graphitisierung; van-der-Pauw; deponierte Energiedichte; tetrahedral amorphous carbon; focused ion beam; phase transformation; graphitization; deposited energy density; ddc:530; rvk:UQ 3400
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-136547; http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-136547; http://www.qucosa.de/fileadmin/data/qucosa/documents/13654/Dissertation_pub.pdf

Ion irradiation of tetrahedral amorphous carbon (ta-C) thin films induces a carbon phase transformation from the electrically insulating sp3 hybridization into the conducting sp2 hybridization. In this work, a detailed study on the electrical resistivity and the microstructure of areas, irradiated with several ion species at 30 keV energy is presented. Continuous ion bombardment yields a drastic drop of the resistivity as well as significant structural modifications of the evolving sp2 carbon phase. It is shown that the resistivity lowering can be attributed to the degree of graphitization in the film. Furthermore, the structural ordering processes are correlated with the ion deposited energy density. It is therefore revealed that the ion-induced phase transformation in ta-C films is a combination of sp3-to-sp2 conversion of carbon atoms and ion-induced ordering of the microstructure into a more graphite-like arrangement. All experiments were done with focused ion beam (FIB) systems by applying FIB lithography of electrical van-der-Pauw test structures. FIB lithography on ta-C layers is presented as a fast and easy technique for the preparation of electrically active micro- and nanostructures in an insulating carbon matrix.