In Situ Simultaneous Growth of Layered SnSe2 and SnSe: a Linear Precursor Approach

The synthesis of layered tin diselenide (SnSe₂) and tin selenide (SnSe) can be achieved independently through distinct nucleation pathways using chemical vapor deposition (CVD). This study successfully achieves the simultaneous growth of SnSe₂ and SnSe, two structurally and functionally distinct tin selenide phases, through hot-wall CVD. For the first time, this is accomplished through an innovative yet facile synthesis method involving a linear arrangement of precursor granules, which effectively overcame the typical limitations of synthesizing SnSe₂ and SnSe from Se powder and SnI₂ granules. The dual-phase growth is realized through precise control of precursor gradients, substrate temperature, and growth duration, with selenium stoichiometry and thermodynamic stability criteria dictated phase formation. A transport model is proposed to describe precursor concentration distribution and reaction rates, elucidating shape evolution and the combined growth of SnSe₂ and SnSe. This study enhances the understanding of competitive growth dynamics and highlights the potential for multifunctional lateral heterostructures and phase-engineered materials for optoelectronic and thermoelectric applications.