Investigation of line-shaped CO2 laser annealing on InN/AlN/sapphire substrates

In this study, a radio-frequency plasma-assisted chemical beam epitaxy (RF-PACBE) system with low growing temperatures was used to grow high-quality indium nitride (InN) thin films. The prepared InN thin films were annealed through a line-shaped CO 2 laser beam irradiation in an atmospheric environment at room temperature. The structural and electrical properties of InN thin films annealed with different CO 2 laser annealing parameters were measured and analyzed. The crystalline grains turned into large and granular morphologies after the InN thin films were annealed under various feeding speeds of a motorized X -axis positioning stage. According to the measured XRD patterns and rocking curves, the InN (0 0 2) peak intensities of laser-annealed thin films were higher than those of as-grown InN thin films. All surface roughnesses and sheet resistances of laser-annealed InN thin films were higher and less than those of as-grown InN thin films. At the set feeding speed of 7.5 mm/s, the laser-annealed InN thin film had the largest grain size of 69.4 nm and the lowest sheet resistance of 20.21 ± 0.27 Ω/sq. The experimental results revealed that the proper annealing conditions could decrease grain boundaries and release internal stresses to enhance the electrical properties through adjusting feeding speeds.