01939nas a2200253   4500008004100000245006500041210006400106260000800170300001400178490000600192520116700198100002401365700001801389700001301407700002101420700002801441700001601469700001601485700002001501700002401521700002401545700001901569856009701588       2013                        eng d00aSensing behavior of atomically thin-layered MoS2 transistors0 aSensing behavior of atomically thinlayered MoS2 transistors  cJUN  a4879-48910 v73 aMost of recent research on layered chalcogenides is understandably focused on single atomic layers. However, it is unclear if single-layer units are the most ideal structures for enhanced gas solid interactions. To probe this issue further, we have prepared large-area MoS2 sheets ranging from single to multiple layers on 300 nm SiO2/Si substrates using the micromechanical exfoliation method. The thickness and layering of the sheets were identified by optical microscope, invoking recently reported specific optical color contrast, and further confirmed by AFM and Raman spectroscopy. The MoS2 transistors with different thicknesses were assessed for gas-sensing performances with exposure to NO2, NH3, and humidity in different conditions such as gate bias and light Irradiation. The results show that, compared to the single-layer counterpart, transistors of few MoS2 layers exhibit excellent sensitivity, recovery, and ability to be manipulated by gate bias and green light. Further, our ab initio DFT calculations on single-layer and bilayer MoS2 show that the charge transfer is the reason for the decrease in resistance in the presence of applied field.1 aLate, Dattatray, J.1 aHuang, Yi-Kai1 aLiu, Bin1 aAcharya, Jagaran1 aShirodkar, Sharmila, N.1 aLuo, Jiajun1 aYan, Aiming1 aCharles, Daniel1 aWaghmare, Umesh, V.1 aDravid, Vinayak, P.1 aRao, C., N. R.  uhttps://library.ncl.res.in/content/sensing-behavior-atomically-thin-layered-mos2-transistors02016nas a2200193   4500008004100000022001400041245011700055210006900172260007700241300001400318490000700332520123600339100002401575700002801599700002401627700002401651700001901675856012801694       2014                        eng d  a1439-423500aThermal expansion, anharmonicity and temperature-dependent Raman spectra of single- and few-layer MoSe2 and WSe20 aThermal expansion anharmonicity and temperaturedependent Raman s  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUN  a1592-15980 v153 a<p>We report the temperature-dependent Raman spectra of single-and few-layer MoSe2 and WSe2 in the range 77-700 K. We observed linear variation in the peak positions and widths of the bands arising from contributions of anharmonicity and thermal expansion. After characterization using atomic force microscopy and high-resolution transmission electron microscopy, the temperature coefficients of the Raman modes were determined. Interestingly, the temperature coefficient of the A(2u)(2) mode is larger than that of the A(1g) mode, the latter being much smaller than the corresponding temperature coefficients of the same mode in single-layer MoS2 and of the G band of graphene. The temperature coefficients of the two modes in single-layer MoSe2 are larger than those of the same modes in single-layer WSe2. We have estimated thermal expansion coefficients and temperature dependence of the vibrational frequencies of MoS2 and MoSe2 within a quasi-harmonic approximation, with inputs from first-principles calculations based on density functional theory. We show that the contrasting temperature dependence of the Raman-active mode A(1g) in MoS2 and MoSe2 arises essentially from the difference in their strainphonon coupling.</p>1 aLate, Dattatray, J.1 aShirodkar, Sharmila, N.1 aWaghmare, Umesh, V.1 aDravid, Vinayak, P.1 aRao, C., N. R.  uhttps://library.ncl.res.in/content/thermal-expansion-anharmonicity-and-temperature-dependent-raman-spectra-single-and-few-0