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

Abstract

In this letter, we demonstrate an efficient threshold voltage ( ${V}_{\mathrm{ th}})$ adjustment technique by depositing single or double dielectric layers on MoS2 field-effect transistors (FETs). We used Al2O3 and SiO2 as the capping layers on the MoS2 FET and observed different average ${V}_{\mathrm{ th}}$ 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 Al2O3 on SiO2 and vice versa, was used for the first time. Consequently, the deposition of SiO2 on Al2O3 and Al2O3 on SiO2 shows an average ${V}_{\mathrm{ th}}$ shifts of +4.92 and +4.02 V, respectively. The defect charges in the dielectric layer can induce band bending in the MoS2 interface and adjust ${V}_{\mathrm{ th}}$ of the MoS2 FET. This result suggests a promising ${V}_{\mathrm{ th}}$ adjustment technique for transition-metal dichalcogenides-based FETs.