Influence of thin film morphology and stacking sequence on Ni-catalyzed graphitization of thin amorphous carbon films

Metal-induced crystallization with layer exchange (MIC w LE) reduces the crystallization temperature of group 14 elements significantly. This is especially interesting for device fabrication on substrates with limited thermal stability. In this contribution, MIC w LE is applied on Ni and C thin film stacks with different stacking sequences. The influence of the thin film morphology and stacking on the layer exchange degree αLE and the graphitic ordering is studied comprehensively in situ and ex situ.
During annealing of the thin films at up to 700 °C, film morphology and stacking sequence had a significant impact on αLE, showing an incomplete LE for the C/Ni stack. The highest αLE of 96%, determined by RBS and ERDA, was achieved for the smoothest samples and Ni/C stacking sequence. Raman spectroscopy and TEM demonstrated the formation of 2D crystalline carbon structures independently of the stacking sequence, while the degree of graphitic ordering increased with decreasing surface roughness. The simultaneous occurrence of LE and graphitization has been demonstrated in situ by RBS and Raman, giving insights into mechanism responsible for carbon crystallization in this system.