Performance Improvement of Multilayered SnS₂ Field Effect Transistors through Synergistic Effect of Vacancy Repairing and Electron Doping Introduced by EDTA

Tin disulfide (SnS2) has a larger band gap (>2.0 eV) than other two-dimensional (2D) materials, which can achieve a higher on/off current ratio, a much lower off-current, and standby power dissipation in future electronics. However, the defects in SnS2, such as sulfur vacancies, always result in very low carrier mobility and on/off current ratio, which are far behind their theoretical values. Herein, we report a synergistic effect of vacancy repairing and electron doping on SnS2 sheets introduced by ethylenediaminetetraacetic acid (EDTA) molecules decoration, which improves the electrical performance of FETs devices. XPS measurements reveal the EDTA can coordinate with the tin atom at the sulfur vacancy, thereby repairing it, while the Hall effect measurements show 1 order improvement of the electron concentration and Hall mobility, up to 4.14 × 1013/cm2 and 237.1 cm2/V·s after 0.3 mol/L EDTA treatment, respectively. Meanwhile, the top-gate FETs with h-BN dielectric layer demonstrate a promising field effect mobility of 8.77 cm2/V·s and a very large on/off ratio of 2 × 107, respectively. The off-current drops to 10–15 A, which guarantees a very low standby power dissipation. Furthermore, the same EDTA treatments were carried out on MoS2, WSe2, and GaSe sheets based FETs, resulting in improvement of electrical properties in n-type 2D materials (i.e., SnS2, MoS2), and deterioration in p-type ones (i.e., WSe2, GaSe), respectively. As a result, the proposed method could be a universal method for improving electrical properties of n-type 2D materials based devices.