Femtosecond Laser Etching of GaN and InGaN Thin Films Grown by Metal Organic Chemical Vapor Deposition

• Published in: Japanese Journal of Applied Physics 2013-08, Vol.52 (8), p.08JK08-08JK08-4
• Main Authors: Ščiuka, Mindaugas, Grinys, Tomas, Dmukauskas, Mantas, Plerpaitė, Viktorija, Melninkaitis, Andrius
• Format: Article
• Language: English
• Subjects: Damage; Diffraction; Etching; Femtosecond; Gallium nitrides; Indium; Indium gallium nitrides; Lasers; Metal organic chemical vapor deposition; Thin films
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.52.08JK08

In this work a possibility of selective GaN and InGaN layer etching via femtosecond laser ablation was investigated. The samples of different indium concentrations were grown by metal organic chemical vapor deposition (MOCVD) technique on sapphire substrates. Prior to the laser treatment all samples were characterized by the means of photoluminescence and X-ray diffraction techniques. Further the laser-induced damage thresholds (LIDT) were estimated in multiple pulse (S-on-1) and single pulse (1-on-1) regimes for 1030, 515, and 343 nm wavelengths covering NIR--UV spectral regions. Experimental results indicated a strong interrelation between LIDT, indium concentration and band-gap. An abrupt change in single pulse LIDT is observed when the multi-photon absorption experiences transition from three to two photon absorption. Furthermore an overview of typical laser induced damage morphologies is performed and discussed. A selective smooth etching of GaN and InGaN layers was obtained when exposing with multiple pulses in UV range.