Patterning the surface structure of transparent hard-brittle material β-Ga2O3 by ultrashort pulse laser

Abstract

Femtosecond laser direct writing technology offers a powerful and advantageous tool for precise three-dimensional (3D) micro/nanofabrication of transparent hard and brittle materials. In this paper, micro-craters, micro/nano-rectangular columns, and microchannels structures with different spatial characteristics are achieved after irradiation of crystalline (100) β-Ga2O3 via an optical-fiber femtosecond laser (515/1030 nm, 285 fs, 100 kHz) with different processing parameters in air ambient. Laser scanning confocal microscope, atomic force microscopy, and Raman spectroscopy are employed to characterize the roughness and constitutive property of the surface structure under tightly focused laser conditions. The influences of different pulse numbers and different pulse energies on the morphology of the pits were investigated. Through precise control and optimization of processing parameters, the formation of cracks and chipping can be effectively avoided. Crack-free ablation holes with smooth edges were fabricated under low-energy (E = 22 nJ) single-pulse conditions. Furthermore, the effects of different laser processing parameters (single-pulse scanning interval, pulse number and scanning repetition times) on the microchannel morphology were also explored. From this work, high-precision micro-hole arrays, micro-nano rectangular column arrays, and microchannels were successfully fabricated on (100) β-Ga2O3 substrates. Due to the interaction of single-pulse femtosecond laser with β-Ga2O3 materials, this fast fabrication method of 3D submicron structures has potential applications in sensing, photonics, or electronics.