(Invited) Memristive Devices based on Two-Dimensional Materials

Abstract

Two-dimensional layered materials are emerging as candidates for neuromorphic switches. So far, several different phenomena have been proposed as device switching mechanisms. These include the lateral movement of ions, either in van der Waals gaps [1] or grain boundary mediated [2], phase changes in 2D materials [3], defect mediated resistive switching [4], or vertical ion movement and subsequent modulation of electronic barriers [5].In this talk, vertically aligned molybdenum disulfide (MoS2) will be discussed as a memristive material that allows ionic transport along its van der Waals gaps. These ions contribute to the electron transport properties across the vertical device structures [6]. In addition, the motion of ions can be used to tune energy barriers at MoS2/semiconductor Schottky junctions [5]. We have identified hydroxyl (OH-) ions that likely originate from catalytic splitting of water molecules in the devices [7]. In addition, vacancies are present in the 2D films that manifest as absorbers for infrared radiation, i.e. wavelengths beyond what is expected from a semiconductor with a bandgap of approximately 1.2 eV [8], [9].AcknowledgementsThe authors acknowledge funding by the European Commission in the Horizon 2020 grant agreements 881603 (Graphene Flagship) and 829035 (QUEFORMAL), the German BMBF grant NEUROTEC (16ES1134) and the DFG projects MOSTFLEX (407080863) and ULTIMOS2 (412113712).