P/N-Type Conversion of 2D MoTe₂ Controlled by Top Gate Engineering for Logic Circuits

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) are key for next-generation logic circuits.
• Top gate field-effect transistors (FETs) offer independent gate control and CMOS compatibility for TMDCs.
• Fabrication of top gate FETs on TMDCs can impact device performance due to deposition methods.

Purpose of the Study:

• Investigate the influence of different top-gate deposition methods on TMDC electrical properties.
• Harness these influences to create homogeneous complementary metal-oxide semiconductor (CMOS) devices on a 2D TMDC platform.
• Demonstrate the feasibility of fabricating functional CMOS circuits using 2D materials.

Main Methods:

• Fabrication of p/n-type controllable top gate FET arrays using 2H-MoTe2.
• Comparison of electron-beam evaporation (EBE) and thermal evaporation for top gate deposition.
• High-resolution transmission electron microscopy (HR-TEM) for defect analysis.
• Fabrication of double-top-gate MoTe2 homogeneous CMOS inverter arrays.

Main Results:

• EBE induces n-doping in 2H-MoTe2, converting p-type to n-type, while thermal evaporation has minimal effect.
• HR-TEM revealed atomic defects in MoTe2 and the MoTe2/Al2O3 interface caused by EBE's high-energy atoms.
• Fabricated CMOS inverters showed clear logic swing, minimal hysteresis, and a high yield of ~93%.
• The process is facile, transfer-free, and compatible with silicon technology.

Conclusions:

• Top-gate deposition method critically affects 2D TMDC device characteristics, enabling p/n-type control.
• EBE-induced defects can be leveraged for n-type channel formation in MoTe2 FETs.
• Homogeneous CMOS circuits with high reliability and yield can be achieved on 2D TMDCs.
• This work advances the integration of 2D TMDCs for practical nanoelectronic applications.