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1.
Adv Mater ; 30(12): e1705542, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29369423

RESUMO

Thin-film transistors (TFTs) based on multilayer molybdenum diselenide (MoSe2 ) synthesized by modified atmospheric pressure chemical vapor deposition (APCVD) exhibit outstanding photoresponsivity (103.1 A W-1 ), while it is generally believed that optical response of multilayer transition metal dichalcogenides (TMDs) is significantly limited due to their indirect bandgap and inefficient photoexcitation process. Here, the fundamental origin of such a high photoresponsivity in the synthesized multilayer MoSe2 TFTs is sought. A unique structural characteristic of the APCVD-grown MoSe2 is observed, in which interstitial Mo atoms exist between basal planes, unlike usual 2H phase TMDs. Density functional theory calculations and photoinduced transfer characteristics reveal that such interstitial Mo atoms form photoreactive electronic states in the bandgap. Models indicate that huge photoamplification is attributed to trapped holes in subgap states, resulting in a significant photovoltaic effect. In this study, the fundamental origin of high responsivity with synthetic MoSe2 phototransistors is identified, suggesting a novel route to high-performance, multifunctional 2D material devices for future wearable sensor applications.

2.
Adv Mater ; 28(12): 2316-21, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-26755196

RESUMO

Large-area and highly crystalline CVD-grown multilayer MoSe2 films exhibit a well-defined crystal structure (2H phase) and large grains reaching several hundred micrometers. Multilayer MoSe2 transistors exhibit high mobility up to 121 cm(2) V(-1) s(-1) and excellent mechanical stability. These results suggest that high mobility materials will be indispensable for various future applications such as high-resolution displays and human-centric soft electronics.


Assuntos
Molibdênio/química , Selênio/química , Transistores Eletrônicos , Cristalização , Microscopia Eletrônica de Transmissão e Varredura , Espectroscopia Fotoeletrônica , Dióxido de Silício/química , Difração de Raios X
3.
Sci Rep ; 5: 15313, 2015 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-26477744

RESUMO

Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm(2)/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τ(rise) ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications.

4.
Adv Mater ; 27(13): 2224-30, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25676825

RESUMO

Local-gate multilayer MoS2 phototransistors exhibit a photoresponsivity of up to 342.6 A W(-1) , which is higher by 3 orders of magnitude than that of global-gate multilayer MoS2 phototransistors. These simulations indicate that the gate underlap is critical for the enhancement of the photoresponsivity. These results suggest that high photoresponsivity can be achieved in indirect-bandgap multilayer MoS2 phototransistors by optimizing the optoelectronic design.

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