Laser-induced damage threshold and laser processing of GaN

The single-shot pulse laser-induced damaging thresholds (LIDTs), an important laser-optical constant of GaN material, were determined to approximately 34 and 65 nJ upon the irradiation of 400 and 800 nm wavelengths, 150 fs duration laser pulse focused by 40x magnification of dry objective lens (a lateral size of focal spot roughly at 1.22 lambda/NA, where NA=0.65). The critical energy of sub-threshold pulses was determined for multi-shot optical damaging. The factors that influenced the LIDTs, optical properties of damaged GaN material and the possibility of laser processing of nitride devices were also discussed.