Authors: H. Lüthje, S. Biehl, R. Bandorf, J.-H. Sick, E. Peiner and A. Tibrewala
Affilation: Fraunhofer IST, Germany
Pages: 800 - 803
Keywords: nano structured amorphous carbon, piezo resistivity
In this contribution we report on investigations of the nano structure, morphology and nano topography of amorphous carbon films with respect to the piezo resistive, electrical and mechanical properties. Therefore a-C, a-C:H and doped a-C:H:X films were prepared at different plasma conditions, e.g. substrate bias variation. The films were mechanically characterized by AFM and Hysitron, which was also used for nano topographic investigations. Selected films were investigated by Raman spectroscopy for revealing the sp2 /sp3 bonding ratio.<br>For investigations of the electrical transport mechanism the carbon films were deposited on n and p-Si wafers. The measurements included resistivity vs temperature plots. Resistivity of the films in general decreases with the increase in temperature. A heterojunction is expected at the film/Si interface. Analysis of the heterojunction leads to the conclusion that the a-C film is of n-type and a-C:H film is of p-type. We propose band diagrams for the a-C:H/p-Si and a-C:H/n-Si heterojunctions.