High-speed ablation etching of GaN semiconductor using femtosecond laser

Using intense femtosecond laser (150 fs, 790 nm, 1 kpps), precise and high- speed laser ablation etching of hexagonal GaN is demonstrated. Etch rate ab ove the ablation threshold is measured to be <5 nm/pulse. An etch rate per second of 25 <mu>m/s is realized at a fluence of 2.2 J/cm(2). Although conv entional long pulsed, tens of ns, KrF laser ablation of the GaN resulted in the formation of a Ga layer on the ablated surface due to laser-induced th ermal decomposition process, the femtosecond laser etching is found to keep the ablated surface unchanged due to non-thermal ablation. Based on the XP S spectra observation the femtosecond laser ablated GaN surface is found to remain unchanged. (C) 2001 Elsevier Science B.V. All rights reserved.