Ablation of GaN Using a Femtosecond Laser

We study the pulse laser ablation of wurtzite gallium nitride (GaN) films grown on sapphire, using the femtosecond laser beam at a central wavelength of 800 nm as the source for the high-speed ablation of GaN films. By measuring the back-scattered Raman spectrum of ablated samples, the dependence of the ablation depth on laser fluence with one pulse was obtained. The threshold laser fluence for ablation of GaN films was determined to be about 0.25 J/cm². Laser ablation depth increases with the increasing laser fluence until the amount of removed material was not further increased. The ablated surface was investigated by an optical surface interference profile meter.