Semiconductor–Semimetal 2D/3D MoS₂/SrRuO₃(111) TMD/TMO Heterojunction-Based ReRAM Devices

Abstract

We have designed and grown MoS 2 /SrRuO 3 (111) (MoS 2 /SRO(111)) semiconductor (SC)/semimetal (SM) heterostructures involving transition-metal dichalcogenide (TMD) and transition-metal oxide (TMO) partners for TMD-based electronic device application. MoS 2 is directly grown on a polar SrRuO 3 (111)/c-Al 2 O 3 substrate by pulsed laser deposition (PLD). A comparative evaluation of few-layer (FL) versus bulk (BL) MoS 2 on polar SRO(111) was performed by using several chemical and physical characterizations. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirm the degenerate states in strained MoS 2 caused by polar SRO(111). In-plane room-temperature resistivity of 1.83 and 1.39 μΩ-cm is obtained for FL and BL MoS 2 /SRO, respectively. Conducting atomic force microscopy (CAFM) was used to elucidate the distribution of in-plane conductive components. The electrical current across the CAFM-tip/MoS 2 /SRO( 111) is primarily controlled by MoS 2 and its interfaces with the tip metal on one side and the oxide semimetal on the other. We find an impressive ReRAM unipolar linear I−V characteristic in the case of FL MoS 2 /SRO (a sharp jump by a factor of 12), while in the BL MoS 2 /SRO (thicker overlayer) case, only a negligible effect is noted. Studies of the work function and Schottky barrier height (SBH) modulation due to the thickness variation of the semiconductor MoS 2 at the SC/SM heterojunction are performed by the electrostatic force microscopy (EFM) to unveil the mechanism of the memristor-type I−V characteristics.