01552nas a2200217   4500008004100000245008600041210006900127260000800196300002700204490000800231520080500239100001901044700002301063700002401086700002101110700002401131700002101155700002401176700002101200856011301221       2013                        eng d00aBand-like transport in high mobility unencapsulated single-layer MoS2 transistors0 aBandlike transport in high mobility unencapsulated singlelayer M  cAPR  aArticle Number: 1731070 v1023 aUltra-thin MoS2 has recently emerged as a promising two-dimensional semiconductor for electronic and optoelectronic applications. Here, we report high mobility (>60 cm(2)/Vs at room temperature) field-effect transistors that employ unencapsulated single-layer MoS2 on oxidized Si wafers with a low level of extrinsic contamination. While charge transport in the sub-threshold regime is consistent with a variable range hopping model, monotonically decreasing field-effect mobility with increasing temperature suggests band-like transport in the linear regime. At temperatures below 100 K, temperature-independent mobility is limited by Coulomb scattering, whereas, at temperatures above 100 K, phonon-limited mobility decreases as a power law with increasing temperature. (C) 2013 AIP Publishing LLC.1 aJariwala, Deep1 aSangwan, Vinod, K.1 aLate, Dattatray, J.1 aJohns, James, E.1 aDravid, Vinayak, P.1 aMarks, Tobin, J.1 aLauhon, Lincoln, J.1 aHersam, Mark, C.  uhttps://library.ncl.res.in/content/band-transport-high-mobility-unencapsulated-single-layer-mos2-transistors01456nas a2200217   4500008004100000245006000041210005900101260000800160300001400168490000600182520078800188100002300976700002400999700002201023700001801045700001601063700002001079700002301099700002401122856009201146       2013                        eng d00aEnhanced field-emission behavior of layered MoS2 sheets0 aEnhanced fieldemission behavior of layered MoS2 sheets  cAUG  a2730-27340 v93 aField emission studies are reported for the first time on layered MoS2 sheets at the base pressure of approximate to 1 x 10(-8) mbar. The turn-on field required to draw a field emission current density of 10 A/cm(2) is found to be 3.5 V/m for MoS2 sheets. The turn-on values are found to be significantly lower than the reported MoS2 nanoflowers, graphene, and carbon nanotube-based field emitters due to the high field enhancement factor (approximate to 1138) associated with nanometric sharp edges of MoS2 sheet emitter surface. The emission current-time plots show good stability over a period of 3 h. Owing to the low turn-on field and planar (sheetlike) structure, the MoS2 could be utilized for future vacuum microelectronics/nanoelectronic and flat panel display applications.1 aKashid, Ranjit, V.1 aLate, Dattatray, J.1 aChou, Stanley, S.1 aHuang, Yi-Kai1 aDe, Mrinmoy1 aJoag, Dilip, S.1 aMore, Mahendra, A.1 aDravid, Vinayak, P.  uhttps://library.ncl.res.in/content/enhanced-field-emission-behavior-layered-mos2-sheets01939nas 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