2019 Volume 24 Pages 21-26
Gallium nitride (GaN) is attractive material for blue light emitting diodes and high-frequency and highpower semiconductors. In general, GaN is sliced by using a wire saw method, although this cutting method has some problems such as thick damaged layer on sliced surface and environmental issue. On the other hand, laser slicing method has the possibility to reduce the kerf loss and the damaged layer compared with the wire saw method. In addition, high quality GaN with low damaged layer can be expected by using an ultrashort pulsed laser irradiation. Therefore, ultrashort pulsed laser was focused inside GaN, and the possibility of its separation by internal modified layer formation was experimentally investigated. GaN is partly decomposed into gallium and nitrogen by ultrashort pulsed laser irradiation, and thin internal modified layer is created by the combination of brittle fracture and decomposition of GaN. The continuous internal modified layer can be obtained by 10 ps pulsed laser irradiation, and GaN can be separated by its internal modified layer.