Evaluation of Strain and Charge‐Transfer Doping in Wet‐Polymeric Transferred Monolayer MoS ₂ : Implications for Field Effect Transistors

ABSTRACT Unlike as‐grown two‐dimensional (2D) materials, transfer onto arbitrary substrates is essential for integration with semiconductor technologies, deterministic moiré superlattices, and flexible circuitry. However, polymeric residues introduced during the film‐transfer process critically modify strain and doping profiles, impeding device fidelity. We investigate the impact of polymer residues from two widely used 2D film transfer techniques: wet‐chemical etching (polymethyl methacrylate (PMMA)‐based) and surface‐energy‐assisted transfer (polystyrene (PS)‐based) of monolayer MoS ₂ (1L‐MoS ₂ ) film. We demonstrate that PMMA residues induce biaxial tensile strain (0.07%) and p ‐type doping (hole density ∼0.74 × 10 ¹³ cm ⁻² ) in residue‐covered regions, while uncovered areas exhibit compressive strain (0.11%). Conversely, PS residues nearly uniformly introduce compressive strain (0.17%) and n ‐type doping (electron density ∼0.89 × 10 ¹³ cm ⁻² ). Kelvin probe force microscopy confirms polymer‐induced doping, and density functional theory calculations support the experimental observations. Field‐effect transistor measurements validate these doping trends, revealing p ‐type (threshold voltage −9.85 V) and n ‐type (threshold voltage −18.25 V) behavior for 1L‐MoS ₂ channel material transferred using PMMA and PS polymers, respectively. The surface‐energy‐assisted transfer method minimizes structural defects, yielding superior device performance with higher ON/OFF ratios (10 ⁶ ) and estimated mobility (10.3 cm ² V ⁻¹ s ⁻¹ ). Our results demonstrate that the transfer methodology provides guidelines for optimizing 1L‐MoS ₂ for high‐performance optoelectronic applications.