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

Abstract

We have designed and grown MoS2/SrRuO3(111) (MoS2/SRO(111)) semiconductor (SC)/semimetal (SM) heterostructures involving transition-metal dichalcogenide (TMD) and transition-metal oxide (TMO) partners for TMD-based electronic device application. MoS2 is directly grown on a polar SrRuO3(111)/c-Al2O3 substrate by pulsed laser deposition (PLD). A comparative evaluation of few-layer (FL) versus bulk (BL) MoS2 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 MoS2 caused by polar SRO(111). In-plane room-temperature resistivity of 1.83 and 1.39 μΩ-cm is obtained for FL and BL MoS2/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/MoS2/SRO(111) is primarily controlled by MoS2 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 MoS2/SRO (a sharp jump by a factor of 12), while in the BL MoS2/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 MoS2 at the SC/SM heterojunction are performed by the electrostatic force microscopy (EFM) to unveil the mechanism of the memristor-type I–V characteristics.