Polarization-Mediated Modulation of Electronic and Transport Properties of Hybrid MoS₂–BaTiO₃–SrRuO₃ Tunnel Junctions

Abstract

Hybrid structures composed of ferroelectric thin films and functional two-dimensional (2D) materials may exhibit unique characteristics and reveal new phenomena due to the cross-interface coupling between their intrinsic properties. In this report, we demonstrate a symbiotic interplay between spontaneous polarization of the ultrathin BaTiO ferroelectric film and conductivity of the adjacent molybdenum disulfide (MoS) layer, a 2D narrow-bandgap semiconductor. Polarization-induced modulation of the electronic properties of MoS results in a giant tunneling electroresistance effect in the hybrid MoS-BaTiO-SrRuO ferroelectric tunnel junctions (FTJs) with an OFF-to-ON resistance ratio as high as 10, a 50-fold increase in comparison with the same type of FTJs with metal electrodes. The effect stems from the reversible accumulation-depletion of the majority carriers in the MoS electrode in response to ferroelectric switching, which alters the barrier at the MoS-BaTiO interface. Continuous tunability of resistive states realized via stable sequential domain structures in BaTiO adds memristive functionality to the hybrid FTJs. The use of narrow band 2D semiconductors in conjunction with ferroelectric films provides a novel pathway for development of the electronic devices with enhanced performance.

Ferroelectric Field Effect Induced Asymmetric Resistive Switching Effect in BaTiO3/Nb:SrTiO3 Epitaxial Heterojunctions

“…Lots of interesting behaviors have been observed in ferroelectric/semiconductor heterojunctions. For example, a greatly enhanced tunneling electroresistance is observed in BaTiO 3 (BTO)/(001)Nb:SrTiO 3 (NSTO) [4, 5] and MoS 2 /BaTiO 3 /SrRuO 3 [6] heterojunctions since both the barrier height and width can be modulated by ferroelectric field effect. A coexistence of the bipolar resistive switching and negative differential resistance has been found in BaTiO 3 /(111)Nb:SrTiO 3 heterojunctions [7].…”

Tsu-Esaki modeling of tunneling currents in ferroelectric tunnel junctions

“…Thus, this can be considered as a step barrier structure and the oscillations observed in Ref. 58 could be due to a resonant tunneling effect. Similarly, resonant tunneling could be at the origin of the oscillations observed in the I-V curve at high voltages in Ref.…”

“…Efforts have also been made to increase TER by adding an extra barrier adjacent to the FE layer. 19,39,58,62 Experimental Au/Co/BTO/LSMO/NdGaO 3 (NdGaO 3 is the substrate) junction was described with a step barrier potential consisting of the BTO ferroelectric layer and a passive layer of CoO x at the Co/BTO interface. The resistive switching was attributed to the field-induced charge redistribution at the ferroelectric-electrode interface changing the CoO x barrier height.…”

“…Also in the case of an intentionally grown extra barrier, the extra dielectric layer is often much thinner than the ferroelectric layer. 39,58 The height of the extra barrier / 2 is varied from 0 to 3.0 eV.…”

Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures

“…Furthermore, MoS 2 is controllable by the electric field when it is in contact with a ferroelectric TMO. With the possibility of tuning the electrical properties of MoS 2 in two different states according to the polarization of the ferroelectric TMO, this idea could be implemented in a ferroelectric tunnel junction device, for example, via the construction of MoS 2 /BaTiO 3 /SrRuO 3 heterostructures . Even though there remains the issue of the interface between MoS 2 and BaTiO 3 , the successful modulation of their electrical conduction was demonstrated experimentally ( Figure a–e).…”