Resistive switching in MoSe2/BaTiO3 hybrid structures

Significance 

Recent technological advances have led to the development of two-dimensional materials such as graphene and metal dichalcogenides and has also paved way for nano-scale electronics development. Specifically, semiconductor transition metal dichalcogenides of the MX2 family have attracted much attention due to their tunable electronic properties which are dependent upon a number of layers in the material. This has enabled the fabrication of devices such as photodetectors, field-effect transistors, chemical sensors and solar cells. Even better, new devices combining transition metal dichalcogenides with ferroelectrics have emerged as novel hotspot for promising applications in electronics and optoelectronics. So far, little regarding the combination of ferroelectrics and transition metal dichalcogenides for resistive random access memories has been published.

Researchers led by professor Olinda Conde at University of Lisbon in Portugal proposed to investigate the resistive switching effect that emerges when ferroelectric barium titanate and few-layer molybdenum diselenide are combined in a single structure. They hoped to elucidate the relation between the ferroelectric polarization and the resistive switching effect, and the mechanism underlying the former. Their work is now published in Journal of Materials Chemistry C and was funded by the Portuguese Foundation for Science and Technology (contracts UID/CTM/04540/2013 and UID/FIS/04650/2013).

The research team commenced their experiments by growing three samples, one of barium titanate, the other of molybdenum diselenide and eventually that of molybdenum diselenide/barium titanate hybrid structures on top of silicon/silicon oxide substrates by chemical vapor deposition and ion-beam sputtering deposition techniques. The surface morphology of the samples was then analyzed by field emission scanning electron microscopy and atomic force microscopy in tapping mode. The researchers then measured capacitance–voltage characteristics using a precision Inductance-Capacitance-Resistance (LCR) meter at an alternating current voltage of 50 mV and frequency of 10 kHz.

Generally, the authors of this paper observed that the capacitance-voltage loops revealed the ferroelectric nature of both Al/Si/SiOx/BTO/Au and Al/Si/SiOx/MoSe2/BTO/Au structures and the high quality of the SiOx/MoSe2 interface in the Al/Si/SiOx/MoSe2/Au structure. Moreover, Al/Si/SiOx/MoSe2/BTO/Au hybrid structures were seen to show electroforming free resistive switching that was explained on the basis of the modulation of the potential distribution at the molybdenum diselenide/barium titanate interface via ferroelectric polarization flipping. The research team also noted that both low resistance state and high resistance state were stable in time when evaluating for potential applications in memory devices and therefore, the hybrid structures displayed a reliable resistive switching behavior.

The study has demonstrated the switchable diode effect of molybdenum diselenide/barium titanate hybrid structures. It has been seen that the origin of the switchable diode effect can be attributed to charge coupling at the molybdenum diselenide/barium titanate interface, which therefore might be related to the ferroelectric polarization reversal process. More so, the coexistence of capacitance–voltage hysteresis and resistive switching characteristics and the equivalence of the coercive field and switching field has confirmed the coupling between ferroelectric polarization reversal and the resistive switching effect. In conclusion, their results indicate that the molybdenum diselenide/barium titanate hybrid structures are promising candidates for non-volatile ferroelectric resistive memories.

Resistive switching in MoSe2BaTiO3 hybrid structures. Advances in Engineering

About the author

Dr. José Pedro Basto da Silva graduated in Physics and Chemistry in 2008 and received his PhD in 2013 from the University of Minho, Braga, Portugal, with a thesis entitled “Growth and structure of layered ferroelectric thin film materials based on stacked structures of BST layers”. Currently he is a Post-doctoral Fellow at the Materials Physics Institute of the University of Porto (IFIMUP-IN) and Centre of Physics of the University of Minho (CFUM), both in Portugal.

His current research interests include understanding the fundamental processes that control the photovoltaic and memory performance of lead-free ferroelectric thin films and ferroelectric/transition metal dichalcogenides hybrid structures.

Email: [email protected] 

About the author

Carolina Almeida Marques received her BSc in Physics in 2014 by the Faculty of Sciences, University of Lisbon (FCUL), in Portugal. She earned her MSc in Condensed Matter Physics and Nanomaterials in the same institution in 2016. Her Master thesis, entitled ‘Growth and Characterization of Low Dimensional Mo Selenide’, was supervised by Prof. Olinda Conde.
In 2017, she received a research scholarship from the Atomic Force Microscopy and Related Techniques Laboratory (FCUL) to study the mechanical properties of different biological systems by AFM.
Currently, she is a PhD student at the School of Physics and Astronomy of the University of St Andrews (UK), studying atomic-scale imaging of magnetism and superconductivity in strongly correlated electron materials by STM.

Email: [email protected]om

About the author

Dr. J. Agostinho Moreira was born in 1966 and received his PhD in 2000 at the University of Porto, Portugal, in the field of solid-state physics. He is currently senior researcher of the Instituto de Física dos Materiais da Universidade do Porto – IFIMUP–IN, and Assistant Professor in the Physics and Astronomy Department of the same university.
His field of expertise is transition metal oxides with multiferroic and magnetoelectric properties, ferroelectric phase transitions, Raman scattering, x-ray and neutron diffraction. Currently, he is interested in applications of the Raman scattering to discriminate cancerous cells.

Email: [email protected]

About the author

Olinda Conde (https://ciencias.ulisboa.pt/perfil/omconde) is an Associate Professor at the Faculty of Sciences of the University of Lisbon (FCUL) and, since 2015, a member of the research Center for Physics and Engineering of Advanced Materials. She graduated in Physics from FCUL and received her PhD in Condensed Matter Physics from the University of Paris VI, in France. She is the Head of the Laser Surface Processing research group that she founded in 1987 at FCUL.
Her research interests include laser-assisted micro- and nanotechnologies, functional thin films and nanostructures, and structural, optical and magnetic properties of thin films. She is a member of the Thin Films Division of IUVSTA.

Email: [email protected]

Reference

J. P. B. Silva, C. Almeida Marques, J. Agostinho Moreira, O. Conde. Resistive switching in MoSe2/BaTiO3 hybrid structures. J. Mater. Chem. C, 2017, volume 5, 10353.

 

Go To Journal of Materials Chemistry C 

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