Selection of metal–tellurium (M–Te) alloy as Recyclable Controlled Te Precursors for Wafer‐Scale Synthesis of M _x Te _y Thin Films

ABSTRACT Wafer‐scale synthesis of metal telluride films has been hindered by the high volatility and limited reactivity of tellurium. To overcome this, we introduce a confined tellurization strategy utilizing in situ formed metal–tellurium (M–Te) alloys as controllable Te sources. Systematic investigation on appropriate metal species through cohesive energy calculations and experiments demonstrates that the cohesive energy of the source metal and metal‐to‐Te atomic ratio in the source bilayer are the key parameters dictating Te flux. Among many metals, Au–Te and Ag–Te alloys provide steady Te flux while preventing the delamination of M/Te bilayer (observed with Pt, Mo, Cu) after metal deposition on Te layer and the undesired co‐evaporation of metal (observed with In, Zn) during Te supply for M _x Te _y synthesis. With the Au–Te alloy, atomically‐smooth, single‐crystalline 4‐inch Si ₂ Te ₃ thin films are produced, which are the largest reported to date. The film thickness can be modulated by adjusting the Au/Te ratio, verified by structural and spectroscopic characterization. The generality of this concept is verified by synthesizing other tellurides, including MoTe ₂ and Cr ₂ Te ₃ . The M–Te alloy source is recyclable by replenishing Te on the alloy, establishing this methodology as a robust and versatile platform for producing a wide range of high‐quality metal telluride films.