Carrier‐Type Modulation and Mobility Improvement of Thin MoTe2

A systematic modulation of the carrier type in molybdenum ditelluride (MoTe2) field‐effect transistors (FETs) is described, through rapid thermal annealing (RTA) under a controlled O2 environment (p‐type modulation) and benzyl viologen (BV) doping (n‐type modulation). Al2O3 capping is then introduced to improve the carrier mobilities and device stability. MoTe2 is found to be ultrasensitive to O2 at elevated temperatures (250 °C). Charge carriers of MoTe2 flakes annealed via RTA at various vacuum levels are tuned between predominantly pristine n‐type ambipolar, symmetric ambipolar, unipolar p‐type, and degenerate‐like p‐type. Changes in the MoTe2‐transistor performance are confirmed to originate from the physical and chemical absorption and dissociation of O2, especially at tellurium vacancy sites. The electron branch is modulated by varying the BV dopant concentrations and annealing conditions. Unipolar n‐type MoTe2 FETs with a high on–off ratio exceeding 106 are achieved under optimized doping conditions. By introducing Al2O3 capping, carrier field effect mobilities (41 for holes and 80 cm2 V−1 s−1 for electrons) and device stability are improved due to the reduced trap densities and isolation from ambient air. Lateral MoTe2 p–n diodes with an ideality factor of 1.2 are fabricated using the p‐ and n‐type doping technique to test the superb potential of the doping method in functional electronic device applications.

[1]  Heejeong Jeong,et al.  Reconfigurable van der Waals Heterostructured Devices with Metal-Insulator Transition. , 2016, Nano letters.

[2]  W. Yoo,et al.  Passivated ambipolar black phosphorus transistors. , 2016, Nanoscale.

[3]  J. Eom,et al.  Two- and four-probe field-effect and Hall mobilities in transition metal dichalcogenide field-effect transistors , 2016 .

[4]  Kazuhito Tsukagoshi,et al.  Carrier Polarity Control in α-MoTe2 Schottky Junctions Based on Weak Fermi-Level Pinning. , 2016, ACS applied materials & interfaces.

[5]  S. Min,et al.  Non‐Lithographic Fabrication of All‐2D α‐MoTe2 Dual Gate Transistors , 2016 .

[6]  M. Engel,et al.  High-Performance p-Type Black Phosphorus Transistor with Scandium Contact. , 2016, ACS nano.

[7]  S. Lodha,et al.  Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation. , 2016, ACS nano.

[8]  Gerhard Klimeck,et al.  Few-layer Phosphorene: An Ideal 2D Material For Tunnel Transistors , 2015, Scientific Reports.

[9]  Xiaochi Liu,et al.  P‐Type Polar Transition of Chemically Doped Multilayer MoS2 Transistor , 2015, Advanced materials.

[10]  Xiaochi Liu,et al.  Self-screened high performance multi-layer MoS₂ transistor formed by using a bottom graphene electrode. , 2015, Nanoscale.

[11]  S. Chae,et al.  High-performance n-type black phosphorus transistors with type control via thickness and contact-metal engineering , 2015, Nature Communications.

[12]  E. Hwang,et al.  High carrier mobility in Si-MOSFETs with a hexagonal boron nitride buffer layer , 2015 .

[13]  J. Robertson,et al.  Chalcogen vacancies in monolayer transition metal dichalcogenides and Fermi level pinning at contacts , 2015 .

[14]  A. Seabaugh,et al.  Reconfigurable Ion Gating of 2H-MoTe2 Field-Effect Transistors Using Poly(ethylene oxide)-CsClO4 Solid Polymer Electrolyte. , 2015, ACS nano.

[15]  A. Suslu,et al.  Environmental Changes in MoTe2 Excitonic Dynamics by Defects-Activated Molecular Interaction. , 2015, ACS nano.

[16]  A. Morpurgo,et al.  Indirect-to-direct band gap crossover in few-layer MoTe₂. , 2015, Nano letters.

[17]  Du Xiang,et al.  Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus , 2015, Nature Communications.

[18]  A. Seabaugh,et al.  Ultimate thin vertical p–n junction composed of two-dimensional layered molybdenum disulfide , 2015, Nature Communications.

[19]  J. Kwon,et al.  Influence of post-annealing on the off current of MoS2 field-effect transistors , 2015, Nanoscale Research Letters.

[20]  Jijun Zhao,et al.  Atomistic insight into the oxidation of monolayer transition metal dichalcogenides: from structures to electronic properties , 2015 .

[21]  Jing Guo,et al.  Dual-gated MoS2/WSe2 van der Waals tunnel diodes and transistors. , 2015, ACS nano.

[22]  L. Lauhon,et al.  Effective passivation of exfoliated black phosphorus transistors against ambient degradation. , 2014, Nano letters.

[23]  Claudia Ruppert,et al.  Optical properties and band gap of single- and few-layer MoTe2 crystals. , 2014, Nano letters.

[24]  Wilman Tsai,et al.  Chloride molecular doping technique on 2D materials: WS2 and MoS2. , 2014, Nano letters.

[25]  Takashi Taniguchi,et al.  Lateral MoS2 p-n junction formed by chemical doping for use in high-performance optoelectronics. , 2014, ACS nano.

[26]  A. Morpurgo,et al.  Surface transport and band gap structure of exfoliated 2H-MoTe2 crystals , 2014, 1407.1219.

[27]  M. Terrones,et al.  Field-effect transistors based on few-layered α-MoTe(2). , 2014, ACS nano.

[28]  A. Javey,et al.  Air-stable surface charge transfer doping of MoS₂ by benzyl viologen. , 2014, Journal of the American Chemical Society.

[29]  Mengwei Si,et al.  The Effect of Dielectric Capping on Few-Layer Phosphorene Transistors: Tuning the Schottky Barrier Heights , 2014, IEEE Electron Device Letters.

[30]  Kazuhito Tsukagoshi,et al.  Ambipolar MoTe2 Transistors and Their Applications in Logic Circuits , 2014, Advanced materials.

[31]  Fei Wang,et al.  Electron-doping-enhanced trion formation in monolayer molybdenum disulfide functionalized with cesium carbonate. , 2014, ACS nano.

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

[33]  Likai Li,et al.  Black phosphorus field-effect transistors. , 2014, Nature nanotechnology.

[34]  Xianfan Xu,et al.  Phosphorene: an unexplored 2D semiconductor with a high hole mobility. , 2014, ACS nano.

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

[36]  Joerg Appenzeller,et al.  WSe2 field effect transistors with enhanced ambipolar characteristics , 2013 .

[37]  C. Frisbie,et al.  A pedagogical perspective on ambipolar FETs. , 2013, Chemphyschem : a European journal of chemical physics and physical chemistry.

[38]  Woong Choi,et al.  Improved growth behavior of atomic-layer-deposited high-k dielectrics on multilayer MoS2 by oxygen plasma pretreatment. , 2013, ACS applied materials & interfaces.

[39]  W. Liu,et al.  Role of metal contacts in designing high-performance monolayer n-type WSe2 field effect transistors. , 2013, Nano letters.

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

[41]  A. Morpurgo,et al.  Quantitative determination of the band gap of WS2 with ambipolar ionic liquid-gated transistors. , 2012, Nano letters.

[42]  J. Kong,et al.  Integrated circuits based on bilayer MoS₂ transistors. , 2012, Nano letters.

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

[44]  P. Ye,et al.  $\hbox{MoS}_{2}$ Dual-Gate MOSFET With Atomic-Layer-Deposited $\hbox{Al}_{2}\hbox{O}_{3}$ as Top-Gate Dielectric , 2011, IEEE Electron Device Letters.

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

[46]  A. Splendiani,et al.  Emerging photoluminescence in monolayer MoS2. , 2010, Nano letters.

[47]  S. Deleonibus,et al.  Reduction of fixed charges in atomic layer deposited Al2O3 dielectrics , 2005 .

[48]  Andre K. Geim,et al.  Electric Field Effect in Atomically Thin Carbon Films , 2004, Science.

[49]  Xianfan Xu,et al.  Phosphorene: An Unexplored 2D Semiconductor with a High Hole , 2014 .