Strain Engineering for Enhancing Carrier Mobility in MoTe 2 Field-Effect Transistors.

Molybdenum ditelluride (MoTe 2 ) exhibits immense potential in post-silicon electronics due to its bandgap comparable to silicon. Unlike other 2D materials, MoTe 2 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 MoTe 2 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 Al 2 O 3 as an additional back-gate dielectric layer on SiO 2 . The MoTe 2 channel is passivated with a thick layer of Al 2 O 3 post-fabrication. This structure significantly improves hole and electron mobilities in MoTe 2 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 MoTe 2 FETs, with a well-defined critical point. This study presents a novel technique to enhance carrier mobility in MoTe 2 FETs, offering promising prospects for improving 2D material performance in electronic applications.