Laser heat-mode micro-/nano-patterning of Ge3Sb2Te6 for tunable metasurfaces

Abstract

Phase change material Ge₃Sb₂Te₆ has received much attention for the fabrication of dynamically tunable metasurfaces owing to the lower electromagnetic losses in the infrared spectral range for both the amorphous and crystalline states. However, fabricating Ge₃Sb₂Te₆-based subwavelength structures by traditional photolithography remains a high-cost and complex process. In this paper, micro-/nanopatterning of Ge₃Sb₂Te₆ through laser heat-mode lithography was achieved. The high resolution of ~ 100 nm was obtained on Ge₃Sb₂Te₆ thin film by optimizing the exposure and developing characteristics. No additional pattern transfer process was needed. Meanwhile, the wet-etching mechanism of Ge₃Sb₂Te₆ was elucidated through X-ray photoelectron spectroscopy. A Ge₃Sb₂Te₆-based tunable metasurface device with the electromagnetically induced transparency function was designed and prepared. The dimension error between the designed structure and the actual prepared structure was kept within 10 nm, which shows a high processing precision. It is a simple and effective solution for the preparation of dynamically tunable metasurface devices for infrared applications.