Optimization of GeSn nanostructures via tuning of femtosecond laser parameters

Abstract

Semiconductor nanostructures are known to exhibit interesting electrical and optical properties, as well as functionalities that are significantly different from their bulk counterparts. These unique characteristics can be attributed to their quantum confinement effects, and large surface-to-volume ratios, along with the fact that their compositions can be tuned. This study proposes a new method for tuning the properties of GeSn nanostructures on a silicon substrate using femtosecond laser direct writing. A series of GeSn nanostructures with different compositions of Sn ranging from nanodots, nanoholes, nanostrips, nanogaps, and nano-cauliflowers were successfully prepared via tuning of femtosecond laser parameters. The morphology, composition of Sn, and crystalline properties of the formed nanostructures were also greatly influenced by the laser fluence and the effective pulse number. The femtosecond laser/GeSn interaction mechanism was thoroughly investigated based on the two-temperature Drude model. This work provides a novel strategy for tuning the bandgap and morphology of GeSn nanostructures, through which the properties of GeSn-based devices can be tailored according to the requirements of practical applications in the fields of microelectronics and photonics.