Multibit data storage states formed in plasma-treated MoS₂ transistors.

New multibit memory devices are desirable for improving data storage density and computing speed. Here, we report that multilayer MoS2 transistors, when treated with plasmas, can dramatically serve as low-cost, nonvolatile, highly durable memories with binary and multibit data storage capability. We have demonstrated binary and 2-bit/transistor (or 4-level) data states suitable for year-scale data storage applications as well as 3-bit/transistor (or 8-level) data states for day-scale data storage. This multibit memory capability is hypothesized to be attributed to plasma-induced doping and ripple of the top MoS2 layers in a transistor, which could form an ambipolar charge-trapping layer interfacing the underlying MoS2 channel. This structure could enable the nonvolatile retention of charged carriers as well as the reversible modulation of polarity and amount of the trapped charge, ultimately resulting in multilevel data states in memory transistors. Our Kelvin force microscopy results strongly support this hypothesis. In addition, our research suggests that the programming speed of such memories can be improved by using nanoscale-area plasma treatment. We anticipate that this work would provide important scientific insights for leveraging the unique structural property of atomically layered two-dimensional materials in nanoelectronic applications.

[1]  Deji Akinwande,et al.  High-performance, highly bendable MoS2 transistors with high-k dielectrics for flexible low-power systems. , 2013, ACS nano.

[2]  Su Seok Choi,et al.  Novel nonvolatile memory with multibit storage based on a ZnO nanowire transistor. , 2010, Nano letters.

[3]  H. Wen,et al.  Control of Schottky barriers in single layer MoS2 transistors with ferromagnetic contacts. , 2013, Nano letters.

[4]  A. Kis,et al.  Correction to Breakdown of High-Performance Monolayer MoS2 Transistors , 2013 .

[5]  Simon Kurasch,et al.  Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping. , 2012, Physical review letters.

[6]  Wei Huang,et al.  Preparation of MoS₂-polyvinylpyrrolidone nanocomposites for flexible nonvolatile rewritable memory devices with reduced graphene oxide electrodes. , 2012, Small.

[7]  L. Zhen,et al.  Surface potential and interlayer screening effects of few-layer MoS2 nanoflakes , 2013 .

[8]  A. Radenović,et al.  Single-layer MoS2 transistors. , 2011, Nature nanotechnology.

[9]  Gerhard Tröster,et al.  Fabrication and transfer of flexible few-layers MoS2 thin film transistors to any arbitrary substrate. , 2013, ACS nano.

[10]  J. Shan,et al.  Atomically thin MoS₂: a new direct-gap semiconductor. , 2010, Physical review letters.

[11]  Zhixian Zhou,et al.  Improved carrier mobility in few-layer MoS2 field-effect transistors with ionic-liquid gating. , 2013, ACS nano.

[12]  J. Kong,et al.  Integrated Circuits Based on Bilayer MoS , 2012 .

[13]  A. Kis,et al.  Nonvolatile memory cells based on MoS2/graphene heterostructures. , 2013, ACS nano.

[14]  Bin Liu,et al.  Sensing behavior of atomically thin-layered MoS2 transistors. , 2013, ACS nano.

[15]  Jae Sung Sim,et al.  Multilevel Data Storage Memory Devices Based on the Controlled Capacitive Coupling of Trapped Electrons , 2011, Advanced materials.

[16]  P. Jeon,et al.  MoS2 nanosheets for top-gate nonvolatile memory transistor channel. , 2012, Small.

[17]  V. A. L. Roy,et al.  Nonvolatile multilevel data storage memory device from controlled ambipolar charge trapping mechanism , 2013, Scientific Reports.

[18]  H. K. Wickramasinghe,et al.  Kelvin probe force microscopy , 1991 .

[19]  Lain-Jong Li,et al.  Highly flexible MoS2 thin-film transistors with ion gel dielectrics. , 2012, Nano letters.

[20]  Young-Jun Yu,et al.  Controlled charge trapping by molybdenum disulphide and graphene in ultrathin heterostructured memory devices , 2013, Nature Communications.

[21]  S. Qin,et al.  Functionalization of monolayer MoS2 by substitutional doping: A first-principles study , 2013 .

[22]  Yoshihiro Iwasa,et al.  Ambipolar MoS2 thin flake transistors. , 2012, Nano letters.

[23]  Y. Iwata,et al.  Pipe-shaped BiCS flash memory with 16 stacked layers and multi-level-cell operation for ultra high density storage devices , 2006, 2009 Symposium on VLSI Technology.

[24]  Xiaogan Liang,et al.  MoS2 transistors fabricated via plasma-assisted nanoprinting of few-layer MoS2 flakes into large-area arrays. , 2013, ACS nano.

[25]  J. Appenzeller,et al.  High performance multilayer MoS2 transistors with scandium contacts. , 2013, Nano letters.

[26]  Bin Liu,et al.  Hysteresis in single-layer MoS2 field effect transistors. , 2012, ACS nano.

[27]  Yoshihiro Iwasa,et al.  Formation of a stable p-n junction in a liquid-gated MoS2 ambipolar transistor. , 2013, Nano letters.

[28]  Michael S. Fuhrer,et al.  High mobility ambipolar MoS2 field-effect transistors: Substrate and dielectric effects , 2012, 1212.6292.

[29]  Gui Yu,et al.  Multibit Storage of Organic Thin‐Film Field‐Effect Transistors , 2009 .

[30]  Hua Zhang,et al.  The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. , 2013, Nature chemistry.

[31]  T. Korn,et al.  Low-temperature photocarrier dynamics in monolayer MoS2 , 2011, 1106.2951.

[32]  Seiichi Aritome,et al.  Advanced flash memory technology and trends for file storage application , 2000, International Electron Devices Meeting 2000. Technical Digest. IEDM (Cat. No.00CH37138).

[33]  Jangho Park,et al.  Integration Technology of 30nm Generation Multi-Level NAND Flash for 64Gb NAND Flash Memory , 2007, 2007 IEEE Symposium on VLSI Technology.

[34]  Qiyuan He,et al.  Memory devices using a mixture of MoS₂ and graphene oxide as the active layer. , 2013, Small.

[35]  Y.C. Chen,et al.  Write Strategies for 2 and 4-bit Multi-Level Phase-Change Memory , 2007, 2007 IEEE International Electron Devices Meeting.

[36]  Hidekazu Tanaka,et al.  Multistate Memory Devices Based on Free‐standing VO2/TiO2 Microstructures Driven by Joule Self‐Heating , 2012, Advanced materials.

[37]  Lian Ji,et al.  Stable few-layer MoS2 rectifying diodes formed by plasma-assisted doping , 2013 .