Growth of highly oriented graphite by ultraviolet nanosecond pulsed laser ablation of monocrystalline diamond

Inducing highly oriented graphite layer as buried conductive media in diamond by laser ablation is crucial for promoting the electronic functionalities of structured monocrystalline diamond. In the present work, we fabricate surface microgrooves with high precision and limited heat affected zone on monocrystalline diamond by low cost ultraviolet nanosecond pulsed laser micromachining. In particular, fruitful highly oriented graphite layer is formed between top transformed amorphous layer and bottom pristine diamond, with visible regular boundaries among them. Raman spectroscopy and high-resolution transmission electron microscopy characterization are jointly utilized to identify the phase transformation-induced microstructure evolution in subsurface of ablated diamond. Furthermore, molecular dynamics simulations are performed to elucidate the underlying ablation mechanisms, as well as predict the dynamic ablation process of nanosecond pulsed laser micromachining of diamond. Finally, the effect of laser fluence on the machined surface morphology and the phase transformation characteristics of the ablated diamond is addressed.