Strain Engineering for Enhancing Carrier Mobility in MoTe₂ Field-Effect Transistors

Molybdenum ditelluride (MoTe₂) exhibits immense potential in post-silicon electronics due to its bandgap comparable to silicon. Unlike other 2D materials, MoTe₂ allows easy phase modulation and efficient carrier type control in electrical transport. However, its unstable nature and low-carrier mobility limit practical implementation in devices. Here, a deterministic method is proposed to improve the performance of MoTe₂ devices by inducing local tensile strain through substrate engineering and encapsulation processes. The approach involves creating hole arrays in the substrate and using atomic layer deposition grown Al₂O₃ as an additional back-gate dielectric layer on SiO₂. The MoTe₂ channel is passivated with a thick layer of Al₂O₃ post-fabrication. This structure significantly improves hole and electron mobilities in MoTe₂ field-effect transistors (FETs), approaching theoretical limits. Hole mobility up to 130 cm⁻² V⁻¹ s⁻¹ and electron mobility up to 160 cm⁻² V⁻¹ s⁻¹ are achieved. Introducing local tensile strain through the hole array enhances electron mobility by up to 6 times compared to the unstrained devices. Remarkably, the devices exhibit metal–insulator transition in MoTe₂ FETs, with a well-defined critical point. This study presents a novel technique to enhance carrier mobility in MoTe₂ FETs, offering promising prospects for improving 2D material performance in electronic applications.