Fabrication and Optimization of Type II Silicon Clathrate Films

Silicon clathrates (SiCL) are a class of cage-structured materials with tuneable optoelectronic properties, offering significant potential for photovoltaic applications. Among them, type II SiCL (NaxSi136) are particularly attractive due to their unique ability to reversibly accommodate guest atoms without compromising the crystal structure. Traditional synthesis methods, such as synthesis under extreme pressure or fabrication under glove boxes, although essential for probing the intrinsic properties of clathrates under well-controlled conditions, are not well-suited for scaling up and are often energy-intensive and require specialized equipment. To overcome these limitations, a scalable, glovebox-free synthesis method based on two thermal decomposition steps was developed to produce silicon clathrate films. Post-synthesis treatment, including thermal pressing and reactive ion etching, was employed to enhance the electrical properties of the material. Phase formation and crystallinity are confirmed by X-ray diffraction and Raman spectroscopy; morphology is assessed by scanning electron microscopy (SEM); and optoelectronic properties are evaluated by photoluminescence. This approach provides a reproducible and scalable route to fabricate type II silicon clathrate films, with promising potential for integration into optoelectronic devices.