Highly Sensitive, Encapsulated MoS2 Photodetector with Gate Controllable Gain and Speed.

Semiconducting, two-dimensional molybdenum disulfide (MoS2) is considered a promising new material for highly sensitive photodetection, because of its atomically thin profile and favorable bandgap. However, reported photodetectors to date show strong variation in performance due to the detrimental and uncontrollable effects of environmental adsorbates on devices due to large surface to volume ratio. Here, we report on highly stable and high-performance monolayer and bilayer MoS2 photodetectors encapsulated with atomic layer deposited hafnium oxide. The protected devices show enhanced electronic properties by isolating them from the ambience as strong n-type doping, vanishing hysteresis, and reduced device resistance. By controlling the gate voltage the responsivity and temporal response can be tuned by several orders of magnitude with R ∼ 10-10(4) A/W and t ∼ 10 ms to 10 s. At strong negative gate voltage, the detector is operated at higher speed and simultaneously exhibits a low-bound, record sensitivity of D* ≥ 7.7 × 10(11) Jones. Our results lead the way for future application of ultrathin, flexible, and high-performance MoS2 detectors and prompt for further investigation in encapsulated transition metal dichalcogenide optoelectronics.

[1]  Arindam Ghosh,et al.  Microscopic origin of low frequency noise in MoS2 field-effect transistors , 2014 .

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

[3]  F. Léonard,et al.  Superlinear composition-dependent photocurrent in CVD-grown monolayer MoS2(1-x)Se2x alloy devices. , 2015, Nano letters.

[4]  Qing Hua Wang,et al.  Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. , 2012, Nature nanotechnology.

[5]  Jun Lou,et al.  CVD-grown monolayered MoS2 as an effective photosensor operating at low-voltage , 2014 .

[6]  Edward H. Sargent,et al.  Sensitive solution-processed visible-wavelength photodetectors , 2007 .

[7]  A. Rose.  Recombination Processes in Insulators and Semiconductors , 1955 .

[8]  Lu Wang,et al.  Photothermoelectric and photovoltaic effects both present in MoS2 , 2015, Scientific Reports.

[9]  Andras Kis,et al.  Thickness-dependent mobility in two-dimensional MoS₂ transistors. , 2015, Nanoscale.

[10]  Andras Kis,et al.  Ultrasensitive photodetectors based on monolayer MoS2. , 2013, Nature nanotechnology.

[11]  Thomas Mueller,et al.  Mechanisms of photoconductivity in atomically thin MoS2. , 2014, Nano letters.

[12]  Soon Cheol Hong,et al.  High‐Detectivity Multilayer MoS2 Phototransistors with Spectral Response from Ultraviolet to Infrared , 2012, Advanced materials.

[13]  R. Wallace,et al.  Atomic Layer Deposition of a High-k Dielectric on MoS2 Using Trimethylaluminum and Ozone , 2014, ACS applied materials & interfaces.

[14]  S. Min,et al.  MoS₂ nanosheet phototransistors with thickness-modulated optical energy gap. , 2012, Nano letters.

[15]  Elucidating the Photoresponse of Ultrathin MoS2 Field-Effect Transistors by Scanning Photocurrent Microscopy , 2013, 1307.5032.

[16]  Qing Zhang,et al.  Few-layer MoS2: a promising layered semiconductor. , 2014, ACS nano.

[17]  J. Grossman,et al.  Broad-range modulation of light emission in two-dimensional semiconductors by molecular physisorption gating. , 2013, Nano letters.

[18]  Edward H. Sargent,et al.  Solution-Processed Quantum Dot Photodetectors , 2009, Proceedings of the IEEE.

[19]  Andres Castellanos-Gomez,et al.  Photocurrent generation with two-dimensional van der Waals semiconductors. , 2015, Chemical Society reviews.

[20]  C. Grigoropoulos,et al.  Analysis of flicker noise in two-dimensional multilayer MoS2 transistors , 2014 .

[21]  Gyu-Tae Kim,et al.  Low-frequency noise in multilayer MoS2 field-effect transistors: the effect of high-k passivation. , 2014, Nanoscale.

[22]  Shengli Chang,et al.  Adsorption of gas molecules on monolayer MoS2 and effect of applied electric field , 2013, Nanoscale Research Letters.

[23]  Jing Guo,et al.  Degenerate n-doping of few-layer transition metal dichalcogenides by potassium. , 2013, Nano letters.

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

[25]  S. Ghatak,et al.  Observation of trap-assisted space charge limited conductivity in short channel MoS2 transistor , 2013, 1308.4858.

[26]  Michael S. Shur,et al.  Low-frequency 1 / f noise in MoS 2 transistors : Relative contributions of the channel and contacts , 2014 .

[27]  Gabriele Navickaite,et al.  Hybrid 2D–0D MoS2–PbS Quantum Dot Photodetectors , 2015, Advanced materials.

[28]  Lain-Jong Li,et al.  Monolayer MoSe2 grown by chemical vapor deposition for fast photodetection. , 2014, ACS nano.

[29]  M. Terrones,et al.  Photosensor Device Based on Few‐Layered WS2 Films , 2013 .

[30]  Wei Chen,et al.  Role of metal contacts in high-performance phototransistors based on WSe2 monolayers. , 2014, ACS nano.

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

[32]  G. Konstantatos,et al.  Ultrasensitive solution-cast quantum dot photodetectors , 2006, Nature.

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

[34]  Hua Zhang,et al.  Single-layer MoS2 phototransistors. , 2012, ACS nano.

[35]  Jr-Hau He,et al.  Few-Layer MoS2 with high broadband Photogain and fast optical switching for use in harsh environments. , 2013, ACS nano.

[36]  Lain-Jong Li,et al.  High‐Gain Phototransistors Based on a CVD MoS2 Monolayer , 2013, Advanced materials.

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

[38]  Jian-Bai Xia,et al.  Photoresponsive and Gas Sensing Field-Effect Transistors based on Multilayer WS2 Nanoflakes , 2014, Scientific Reports.

[39]  A. Sandhu,et al.  High photosensitivity few-layered MoSe2 back-gated field-effect phototransistors , 2014, Nanotechnology.

[40]  Gyuchull Han,et al.  Giant Photoamplification in Indirect‐Bandgap Multilayer MoS2 Phototransistors with Local Bottom‐Gate Structures , 2015, Advanced materials.

[41]  Dumitru Dumcenco,et al.  Electrical transport properties of single-layer WS2. , 2014, ACS nano.

[42]  Arindam Ghosh,et al.  Nature of electronic states in atomically thin MoS₂ field-effect transistors. , 2011, ACS nano.

[43]  P. Avouris,et al.  Photodetectors based on graphene, other two-dimensional materials and hybrid systems. , 2014, Nature nanotechnology.