Fractal growth mechanism of sp³-bonded 5H-BN microcones by plasma-assisted pulsed-laser chemical vapor deposition

Here we propose a repetitive photochemical reaction and diffusion model for the fractal pattern formation of sp³-bonded 5H-BN microcones in laser-assisted plasma chemical vapor deposition, which was observed experimentally and reported previously. This model describing the behavior of the surface density of precursor species gave explanations to (1) the "line-drawing" nature of the patterns, (2) the origin of the scale-invariant self-similarity (fractality) of the pattern, and (3) the temperature-dependent uniform to fractal transition. The results have implications for controlling the self-organized arrangements of electron-emitter cones at the micro-and nanoscale by adjusting macroscopically the boundary condition (L_X,L_Y) for the deposition, which will be very effective in improving the electron field emission properties.