Highly oriented graphite produced by femtosecond laser on diamond

Abstract

To transform a monocrystalline diamond into monocrystalline graphite, the exposure of an ultrafast laser to a (111) diamond face was investigated for the first time. The single pulse of the third harmonic of a Ti:sapphire laser (100 fs, 266 nm) was used to produce graphitized inclusions embedded in a (111) diamond substrate. Three different regimes of (111) diamond graphitization are discussed in this paper. Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the graphitized material, which was found to resemble highly oriented graphite at certain laser fluencies. The proposed approach to the problem of perfect local diamond graphitization is an important step toward creating all-carbon composite systems consisting of conductive and dielectric phases.

Laser-Induced Graphitization of Diamond Under 30 fs Laser Pulse Irradiation

“…14 Processing diamond above its graphitization threshold with ns and/or ps pulses is associated with a higher volume/mass removal but also with a significant and unavoidable formation of HAZ as longer pulses generate plasma plumes of higher ion density and electron temperature. 9,15 fs pulses and, in particular, the sub-50 fs pulses are able to deliver a fluence well above diamond's graphitization threshold (0.3 J/ cm 2 ) 16 at or near the ablation threshold (∼3.0−4.0 J/cm 2 ) 17,18 and, notionally, without any thermal damage. Simulations suggest that under ns or longer laser pulse durations, graphitization propagates vertically, affecting the bulk of the focal volume, leading to the formation of largely amorphous sp 3 :sp 2 interfaces following the laser treatment.…”

“…The volumetric processing efficiency, that is, the sp 3 into sp 2 phase conversion, followed by a subtractive sp 2 fraction removal, remains low for all pulse widths and the lengths of the laser pulse being used, as the thermal diffusion is primarily limited to the focal volume . Processing diamond above its graphitization threshold with ns and/or ps pulses is associated with a higher volume/mass removal but also with a significant and unavoidable formation of HAZ as longer pulses generate plasma plumes of higher ion density and electron temperature. , fs pulses and, in particular, the sub-50 fs pulses are able to deliver a fluence well above diamond’s graphitization threshold (0.3 J/cm 2 ) at or near the ablation threshold (∼3.0–4.0 J/cm 2 ) , and, notionally, without any thermal damage. Simulations suggest that under ns or longer laser pulse durations, graphitization propagates vertically, affecting the bulk of the focal volume, leading to the formation of largely amorphous (a) sp 3 :sp 2 interfaces following the laser treatment. , By contrast, with fs laser pulses, graphitization of diamond occurs fully layer by layer in a pseudo “peel off” process, resulting in the formation of a clean diamond surface after the ablation, which is highly desirable for applied applications.…”

Ultrafast Laser Processing of Diamond Materials: A Review

“…In the UV range (close to the value of diamond indirect bandgap of 5.47 eV) the absorbance is close to 95%. Femtosecond laser treatment leads to the appearance of surface defect states in the band gap of diamond, which can act as traps or recombination centers [29,[44][45][46].…”

Transformations of fast neutron-irradiated diamonds under femtosecond laser radiation

“…Radiation damage of diamond also leads to the "diamond-graphite" phase transition. Single shot femtosecond laser processing of the (111) diamond face was demonstrated to be a promising tool for constructing all-carbon composite systems consisting of conductive and dielectric phases [7]. Ion implantation and ion milling can also be used to fabricate diamond optical components suitable for quantum information processing technology, diamond micro-and nanoelectromechanical systems, and other optoelectronic devices [8][9].…”