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 Al2 O3 as an additional back-gate dielectric layer on SiO2 . The MoTe2 channel is passivated with a thick layer of Al2 O3 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.
Keywords: Al2O3; MoTe2; carrier mobility; metal-insulator transition; tensile strain.
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