Nanosecond-laser-induced graphitization and amorphization of thin nano-crystalline graphite films
To develop optically-controlled resistive memories, we study the laser-induced graphitization and amorphization of vertically oriented nano-crystalline graphite (vnC-G) thin films deposited with the filtered cathodic vacuum arc method. vnc-G films consist in graphitic planes perpendicular to the substrate within a matrix of amorphous carbon [1]. Controlled graphitization and amorphization of carbon materials is a long-standing issue with unclear mechanisms [2-5]. Here, we report on graphitization and amorphization of vnc-G controlled by single 532 nm-5 ns laser pulses of various intensities. We demonstrate partial reversibility between graphitization and amorphization, opening the way toward device applications. Depending on pulse energy, samples also display an intricate typology of degradations, from periodic ripples, cracks, upheavals and spheroids to traces of explosions. Supported by a finite-element thermo-mechanical model, we discuss the impact of the orientation of the graphitic planes.