Study on the resistance distribution at the contact between molybdenum disulfide and metals.

Contact resistance hinders the high performance of electrical devices, especially devices based on two-dimensional (2D) materials, such as graphene and transition metal dichalcogenide. To engineer contact resistance, understanding the resistance distribution and carrier transport behavior at the contact area is essential. Here, we developed a method that can be used to obtain some key parameters of contact, such as transfer length (Lt), sheet resistance of the 2D materials beneath the contacting metal (Rsh), and contact resistivity between the 2D materials and the metal electrode (ρc). Using our method, we studied the contacts between molybdenum disulfide (MoS2) and metals, such as titanium and gold, in bilayer and few-layered MoS2 devices. Especially, we found that Rsh is obviously larger than the sheet resistance of the same 2D materials in the channel (Rch) in all the devices we studied. With the increasing of the back-gate voltage, Lt increases and Rsh, ρc, Rch, and the contact resistance Rc decrease in all the devices we studied. Our results are helpful for understanding the metal–MoS2 contact and improving the performances of MoS2 devices.

[1]  Pablo Jarillo-Herrero,et al.  Intrinsic electronic transport properties of high-quality monolayer and bilayer MoS2. , 2013, Nano letters.

[2]  Youngki Yoon,et al.  How good can monolayer MoS₂ transistors be? , 2011, Nano letters.

[3]  F. Xia,et al.  The origins and limits of metal-graphene junction resistance. , 2011, Nature nanotechnology.

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

[5]  Shi-Li Zhang,et al.  Metal Silicides in CMOS Technology: Past, Present, and Future Trends , 2003 .

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

[7]  W. Mönch,et al.  Valence-band offsets and Schottky barrier heights of layered semiconductors explained by interface-induced gap states , 1998 .

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

[9]  Mengwei Si,et al.  Switching mechanism in single-layer molybdenum disulfide transistors: an insight into current flow across Schottky barriers. , 2014, ACS nano.

[10]  P. Ye,et al.  Molecular Doping of Multilayer ${\rm MoS}_{2}$ Field-Effect Transistors: Reduction in Sheet and Contact Resistances , 2013, IEEE Electron Device Letters.

[11]  François Léonard,et al.  Electrical contacts to one- and two-dimensional nanomaterials. , 2011, Nature nanotechnology.

[12]  R. Wallace,et al.  The unusual mechanism of partial Fermi level pinning at metal-MoS2 interfaces. , 2014, Nano letters.

[13]  A. Toriumi,et al.  Contact resistivity and current flow path at metal/graphene contact , 2010 .

[14]  Hugen Yan,et al.  Anomalous lattice vibrations of single- and few-layer MoS2. , 2010, ACS nano.

[15]  Kyeongjae Cho,et al.  Metal contacts on physical vapor deposited monolayer MoS2. , 2013, ACS nano.

[16]  Stephen McDonnell,et al.  Defect-dominated doping and contact resistance in MoS2. , 2014, ACS nano.

[17]  P. Ye,et al.  Channel length scaling of MoS2 MOSFETs. , 2012, ACS nano.

[18]  B. Radisavljevic,et al.  Mobility engineering and a metal-insulator transition in monolayer MoS₂. , 2013, Nature materials.

[19]  John Robertson,et al.  Sulfur vacancies in monolayer MoS2 and its electrical contacts , 2013 .

[20]  Dominique Baillargeat,et al.  From Bulk to Monolayer MoS2: Evolution of Raman Scattering , 2012 .

[21]  M. Kamalakar,et al.  High-performance molybdenum disulfide field-effect transistors with spin tunnel contacts. , 2014, ACS nano.

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

[23]  B. Radisavljevic,et al.  Visibility of dichalcogenide nanolayers , 2010, Nanotechnology.

[24]  Frank Schwierz,et al.  Graphene Transistors: Status, Prospects, and Problems , 2013, Proceedings of the IEEE.

[25]  A. Javey,et al.  High-performance single layered WSe₂ p-FETs with chemically doped contacts. , 2012, Nano letters.

[26]  Eric Pop,et al.  Nanoscale Joule heating, Peltier cooling and current crowding at graphene–metal contacts , 2011, Nature Nanotechnology.

[27]  Luigi Colombo,et al.  Contact resistance in few and multilayer graphene devices , 2010 .

[28]  V. Shenoy,et al.  Tuning the electronic properties of semiconducting transition metal dichalcogenides by applying mechanical strains. , 2012, ACS nano.

[29]  S. Lau,et al.  Exceptional tunability of band energy in a compressively strained trilayer MoS2 sheet. , 2013, ACS nano.

[30]  J. Appenzeller,et al.  Where does the current flow in two-dimensional layered systems? , 2013, Nano letters.

[31]  Juin J. Liou,et al.  A review of recent MOSFET threshold voltage extraction methods , 2002, Microelectron. Reliab..

[32]  David Tománek,et al.  Designing electrical contacts to MoS2 monolayers: a computational study. , 2012, Physical review letters.