Thin epitaxial GaN films ablated by a pulsed KrF excimer laser

We have studied the laser-induced ablation thresholds in heteroepitaxial gallium nitride (GaN) layers grown on sapphire substrates. The relationship between the laser-ablated GaN film thickness and the flux density of VUV laser radiation with a wavelength of 248 nm has been established. The photo- and thermoablation thresholds have been observed at a radiation intensity of 252 and 520 mJ/cm(2), respectively. The enthalpy of GaN dissociation estimated from an analysis of thermoablation data is 150 kJ/mol, in agreement with the published reference values. The experimental results were implemented in the technology of blue light-emitting diodes (LEDs), which allowed the LED output yield to be significantly increased.