Resistive Switching in Polyvinylpyrrolidone/Molybdenum Disulfide Composite-Based Memory Devices

Z.W. Dlaminia, b, S. Vallabhapurapuc, A. Srinivasand, S. Wue, V.S. Vallabhapurapua aPhysics Department, College of Science, Engineering, and Technology (CSET), University of South Africa, Pioneer Ave 28, 1710 Johannesburg, South Africa bDepartment of Maths, Science, and Technology Education (MSTE), Faculty of Humanities, Central University of Technology, President Brand 20, 9301 Bloemfontein, South Africa cSchool of Computing, College of Science, Engineering, and Technology (CSET), University of Technology, Pioneer Ave 28, 1710 Johannesburg, South Africa dDepartment of Physics, Indian Institute of Technology Guwahati, Surjyamukhi Road, 781039 Guwahati, India eSchool of Engineering, Faculty of Science and Engineering, Macquarie University, Balaclava Rd, NSW 2109 Sydney, Australia

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Four types of resistive random access memory structures with an active layer comprising: (1) MoS2 (device A), (2) PVP (device B), (3) PVP and MoS2 bilayer (device C), and (4) PVP + MoS2 nanocomposites with 10 (device D), 20 (device E), 30 (device F) and 40 wt% (device G) MoS2, have been fabricated with Al and Ag as bottom and top electrodes, respectively. A study of resistive switching and electrical conduction mechanisms of these resistive random access memory modules revealed that devices A and B did not exhibit switching characteristics. Device C showed a combination of bipolar and threshold switching with a low switching voltage of 0.40 V. Device G portrayed bipolar switching at 0.56 V. In device C, space charge-limited conduction with a transition voltage Vtr=0.24 V was observed, whereas in device G, Ohmic behaviour between 0.0 and 0.22 V, followed by trapping of charge in the 0.22-0.56 V regime before switching, was noticed. Both devices C and G showed a reasonable (≥102) ON/OFF ratio. In nanocomposite devices, an increase in MoS2 content resulted in an increase in electrical conductivity in the Ohmic region, leading to threshold switching at 30 wt% (device F) and ultimately bipolar switching at 40 wt% (device G). These studies have shown that both switching and conduction mechanisms are sensitive to the type and composition of the active layer in the devices studied.

DOI:10.12693/APhysPolA.141.439 topics: resistive switching, conduction mechanism, MoS2, bilayer