Wafer-Scale Deposition of 2D SnSe with Monolayer-Thickness Precision.

2D SnSe presents considerable opportunities for transistors, optoelectronics, and photonics if wafer-scale deposition with monolayer thickness control can be achieved. This work answers this critical need by developing a mirror rastering pulsed laser deposition (PLD) approach that enables wafer scale coverage of SnSe with monolayer thickness precision and atomic scale surface roughness (0.29 nm). SnSe thin films are deposited onto 7.5 × 5 cm flexible mica substrate in monolayer increments from 3.5 to 6.1 nm by mirror rastered PLD. All films exhibit stoichiometric (200) oriented Pnma SnSe with consistent phase and thickness across the length of the wafer. Furthermore, sheet resistance is constant with an average of 0.52 GΩ/sq across a 6 cm span and remains stable upon mechanical flexing. This work demonstrates the wafer-scale SnSe deposition with precise thickness control needed to enable next-generation 2D electronics and optoelectronics.