Abstract Empty space in germanium (ESG) or germanium-on-nothing (GON) are unique self-assembled germanium structures with multiscale cavities of various morphologies. Due to their simple fabrication process and high-quality crystallinity after self-assembly. they can be applied in various fields including micro-/nanoelectronics. optoelectronics. https://www.sjcaindia.com/product-category/e-cigs/