The effect of interdiffusion during formation of epitaxial Ca intercalated layered silicene film on its thermoelectric power factor

Abstract

Deformation of silicene buckled structure attracts great interest for the possibility of ultrahigh thermoelectric power factor. Therefore, the control method of silicene buckled structure is needed. Here, we developed the method to control composition ratio in epitaxial Ca intercalated layered silicene (CaSi2) film formed by solid phase epitaxy through an atomic interdiffusion between Ca films and Si substrate because of the possible existence of the relation between silicene buckled structure in CaSi2 film and the composition ratio. The interdiffusion is controlled by introducing hydrogen-terminated layer as an interface layer between Ca and Si substrate, resulting in the control of the composition ratio in CaSi2 film. Moreover, we find that the CaSi2 films with different composition ratio exhibit different thermoelectric power factors. This study reveals that introducing the interface layer for interdiffusion control is an effective way to control the composition ratio and to form metastable high-buckled silicene with high power factor.

Growth of metastable 2H-CaSi2 films on Si(111) substrates with ultrathin SiO2 films by solid phase epitaxy

“…Then the lattice misfit at the interface of the CaSi 2 film and Si(111) substrate is discussed. The orientation relationship between the Si(111) substrate and the epitaxial CaSi 2 film (or grains) in the present work was (001) CaSi2 //(111) Si , [1][2][3][4][5][6][7][8][9][10] CaSi2 // Si , and [001] CaSi2 //[111] Si . Thus, the lattice misfit is calculated from the lattice parameter, a, for each CaSi 2 phase and the d 110 lattice spacing of the Si substrate.…”

Epitaxial growth of Ca(Ge1−xSnx)2 with group IV 2D layers on Si substrate

“…31,32) In this previous study, the compositional analysis revealed the formation of Si-rich CaSi 2 films, indicating that the deformation of the buckling structure could be related to non-stoichiometry. 33,34) Therefore, controlling atom species, elemental composition and strain near the interface, etc., can largely deform the buckling structure, leading to ultrahigh S 2 σ. Among Caintercalated group IV 2D materials, CaGe 2 can exhibit higher TE performance than CaSi 2 because the theoretical study reported that germanene could have higher μ than silicene.…”