Efficient Threshold Voltage Adjustment Technique by Dielectric Capping Effect on MoS2 Field-Effect Transistor

In this letter, we demonstrate an efficient threshold voltage (V th ) adjustment technique by depositing single or double dielectric layers on MoS 2 field-effect transistors (FETs). We used Al 2 O 3 and SiO 2 as the capping layers on the MoS 2 FET and observed different average V th shifts of -2.39 and +7.13 V, respectively. In order to further the controllability of the dielectric capping effect, the deposition of double dielectric layers, specifically Al 2 O 3 on SiO 2 and vice versa, was used for the first time. Consequently, the deposition of SiO 2 on Al 2 O 3 and Al 2 O 3 on SiO 2 shows an average V th shifts of +4.92 and +4.02 V, respectively. The defect charges in the dielectric layer can induce band bending in the MoS 2 interface and adjust V th of the MoS2 FET. This result suggests a promising V th adjustment technique for transition-metal dichalcogenides-based FETs.