An investigation of aluminum nitride thin films patterned by femtosecond laser

Abstract

In this study, a femtosecond laser etching method is proposed to pattern an aluminum nitride (AlN) film, grown by metal-organic chemical vapor deposition on sapphire. Via control of typical pulse energies, the designed pattern was precisely written in the AlN film. The morphology of the patterned structures was characterized using a three-dimensional laser scanning confocal microscope and a scanning electron microscope; crystalline quality and film strain were analyzed using a Raman spectrometer and a transmission electron microscope. The results indicate that consistent morphologies were achieved with only slight changes to the crystalline quality. The tensile stress of the AlN film was released, and the film surface was slightly compressed after laser patterning. Thus, femtosecond etching has the potential to be an in situ patterning method during film growth.