Cascaded Logic Gates Based on High-Performance Ambipolar Dual-Gate WSe2 Thin Film Transistors

TL;DR

This paper demonstrates high-performance ambipolar dual-gate WSe2 transistors capable of cascadable logic gates with low power consumption, high speed, and flexible circuit design, advancing 2D material-based logic technology.

Contribution

It introduces the first cascadable logic gates using ambipolar WSe2 transistors with detailed analysis of gate behavior and noise margins, enabling low-power, high-speed flexible circuits.

Findings

Achieved high on-off ratios of 10^8 and 10^6 in WSe2 transistors.

Demonstrated cascadable logic gates including inverters, XOR, NAND, NOR, with minimal static power.

Analyzed noise margins and introduced VT-drop circuits for simplified, low-power logic design.

Abstract

Ambipolar dual-gate transistors based on two-dimensional (2D) materials, such as graphene, carbon nanotubes, black phosphorus, and certain transition metal dichalcogenides (TMDs), enable reconfigurable logic circuits with suppressed off-state current. These circuits achieve the same logical output as CMOS with fewer transistors and offer greater flexibility in design. The primary challenge lies in the cascadability and power consumption of these logic gates with static CMOS-like connections. In this article, high-performance ambipolar dual-gate transistors based on tungsten diselenide (WSe2) are fabricated. A high on-off ratio of 10^8 and 10^6, a low off-state current of 100 to 300 fA, a negligible hysteresis, and an ideal subthreshold swing of 62 and 63 mV/dec are measured in the p- and n-type transport, respectively. For the first time, we demonstrate cascadable and cascaded logic gates using ambipolar TMD transistors with minimal static power consumption, including inverters, XOR, NAND, NOR, and buffers made by cascaded inverters. A thorough study of both the control gate and polarity gate behavior is conducted, which has previously been lacking. The noise margin of the logic gates is measured and analyzed. The large noise margin enables the implementation of VT-drop circuits, a type of logic with reduced transistor number and simplified circuit design. Finally, the speed performance of the VT-drop and other circuits built by dual-gate devices are qualitatively analyzed. This work lays the foundation for future developments in the field of ambipolar dual-gate TMD transistors, showing their potential for low-power, high-speed and more flexible logic circuits.