Composition-modulated anti-ambipolar behavior enabled by two-dimensional GeSxSe1−x/SnS2 van der Waals heterostructures for high-performance logic inverters

Abstract

Logic inverters, which lay the foundation for the functionality of large-scale integrated circuits, are achieved using anti-ambipolar transistors (AATs) based on two-dimensional (2D) van der Waals heterojunctions (vdWH). However, the impact of the doping strategy on the figures of merit of logic inverters based on 2D vdWH AATs has not been comprehensively analyzed. Herein, 2D free-standing GeS_xSe_1−x (0 ≤ x ≤ 0.73) with precisely tunable composition was grown to fabricate GeS_xSe_1−x/SnS₂ vdWH AATs to achieve an optimal logic inverter. By leveraging elemental modulation in GeS_xSe_1−x, the proposed vdWH was tuned from type-II to type-III band alignment, allowing for a distinctive tunneling process at various bias conditions. The proposed devices with poor S content exhibited a better peak-to-valley ratio of 6.6 × 10³ at x = 0.29 and a maximum peak current of 1.4 × 10⁻⁷ A at x = 0. Furthermore, the inverter built with the GeS_xSe_1−x/SnS₂ device achieved the highest voltage gain of 8.83 at x = 0.29, while the device with an S-rich AAT delivered a low static power of 12.1 pW, which is attributed to the optimization of band engineering and the low driving voltage under the bottom h-BN/Au structure. This work contributes insights into the expansion of alloy engineering in the construction of high-performance multi-valued logic inverters.