中文
Shangguan Shiyong, a postgraduate student of CALM (first author), Professor Qi Dongfeng (corresponding authors), and Professor Zheng Hongyu published a paper entitled “Study on the periodic structure of polycrystalline GeSn prepared by femtosecond pulse laser direct writing” in Optics and Laser Technology.
Pulsed laser annealing (PLA) is an effective way to prepare crystalline GeSn films with high Sn content. However, most of the current studies have only reported the appearance of disordered rough structures on the surface of the material during pulsed laser-induced crystallization of amorphous semiconductors. The changes in the morphological characteristics of the GeSn material surface during laser-induced crystallization have not been systematically investigated. Therefore, we investigated the changes in the surface morphology of a-GeSn films deposited on SiO2 substrates by magnetron sputtering during fs laser-induced crystallization. With suitable laser processing parameters, we successfully induced polycrystalline periodic nanodot structures on the surface of a GeSn films with a thickness of approximately 100 nm (the thickness of film is measured by profilometer) using the fs laser (wavelength: 800 nm; pulse duration: 130 fs). A Ge-Ge phonon peak is exhibited near 290 cm− 1 in the Raman spectrum, indicating that the sample crystallized after fs laser irradiation. In addition, the crystalline properties of the laser-induced periodic surface structures (LIPSS) are also characterized by XRD. The transient heating by the fs laser allows for a rapid non-equilibrium temperature transition at the film surface, which helps to inhibit the segregation of the Sn component. This study provides a new method for the one-step preparation of GeSn nanodots with high Sn content and high crystallization quality.
Figure.1.a) SEM image, (b) AFM image, and (c) characterization of Raman spectra of the LIPSS structure
