Abstract Two-dimensional (2D) material is drawing considerable attention as a promising thermoelectric material. This study establishes the formation method of renewed Ca-intercalated group IV 2D materials, Ca(Ge 1− x Sn x ) 2 crystals including germanene-based 2D layers. The solid phase epitaxy allows us to form epitaxial Ca(Ge 1− x Sn x ) 2 on Si. Atomic force microscopy reveals that the Ca(Ge 1− x Sn x ) 2 has island structures. X-ray diffraction proved the epitaxial growth of the Ca(Ge 1− x Sn x ) 2 island structures and the increase of the c -axis lattice constant with Sn content increase. The formation of this renewed intermetallic compound including group IV 2D layer opens an avenue for high performance thermoelectric generator/Si.