Investigating laser induced phase engineering in MoS2 transistors

Phase engineering of MoS2 transistors has recently been demonstrated and has led to record low contact resistances. The phase patterning of MoS2 flakes with laser radiation has also been realized via spectroscopic methods, which invites the potential of controlling the metallic and semiconducting phases of MoS2 transistors by simple light exposure. Nevertheless, the fabrication and demonstration of laser patterned MoS2 devices starting from the metallic polymorph has not been demonstrated yet. Here, we study the effects of laser radiation on 1T/1T'-MoS2 transistors with the prospect of driving an in-situ phase transition to the 2H-polymorph through light exposure. We find that although the Raman peaks of 2H-MoS2 become more prominent and the ones from the 1T/1T' phase fade after the laser exposure, the semiconducting properties of the laser patterned devices are not fully restored and the laser treatment ultimately leads to degradation of the transport channel

Thickness dependent interlayer transport in vertical MoS2 Josephson junctions

We report on observations of thickness dependent Josephson coupling and multiple Andreev reflections (MAR) in vertically stacked molybdenum disulfide (MoS2) - molybdenum rhenium (MoRe) Josephson junctions. MoRe, a chemically inert superconductor, allows for oxide free fabrication of high transparency vertical MoS2 devices. Single and bilayer MoS2 junctions display relatively large critical currents (up to 2.5 uA) and the appearance of sub-gap structure given by MAR. In three and four layer thick devices we observe orders of magnitude lower critical currents (sub-nA) and reduced quasiparticle gaps due to proximitized MoS2 layers in contact with MoRe. We anticipate that this device architecture could be easily extended to other 2D materials.Comment: 18 pages, 6 figures including Supporting Informatio

Data showing the effects of geotechnical properties of lateritic soil mixed with coconut shell powder in Ado-Ekiti, south western Nigeria

Abstract: In this data, the effect of locally available additive Coconut shell powder (CSP) substitute in determining the geotechnical properties of Ado Ekiti soil was assessed. The samples were collected from two borrow pits, Ado-Ijan road and Ado-Ilawe road, at two points each, and were treated using substitute of coconut shell powder, considering several percentages of its content at 0%, 2%, 4%, 6%, 8% and 10%. Laboratory tests such as specific gravity, consistency limit test, grain size distribution test, compaction test, CBR test, triaxial compression test, permeability test was conducted on the soil samples collected, and untreated soil was determined. The summary shows that the liquid limit, plastic limit, Plasticity Index, Maximum Dry Density and Optimum Moisture Content increases with increase in percentage of the additive and later decrease at higher percentage of additive, mostly at 8% and 10% respectively. The value of California Bearing ratio in percentage increases as the percentage of additive increases, although at 0% additive, the soil does not meet specification of road construction and the value of permeability ‘k’ also increases. The summary of triaxial test also shows increase in the strength properties of the soil at certain percentage likewise, the summary of unconfined compressive strength shows same. This indicates that the additives improves..

WIND ENERGY POTENTIAL FOR POWER GENERATION OF A LOCAL SITE IN GUSAU, NIGERIA

This study was used to evaluate the wind energy potential of a meteorological site in Gusau, the capital city of Zamfara state, in Nigeria. Twenty-one years (1987−2007) of three-hourly monthly mean wind data from the Nigeria Meteorological Department were assessed and subjected to two-parameter Weibull and other statistical analyses to determine the resource potential of the site for periods of months, seasons, and years. Attempts were made to compare the mean measured data with estimated data, and the Kolmogorov-Smirnov statistics were employed to show the site's wind profile's consistence with Weibull two-parameter distribution. The results showed that the monthly values of k and c ranged between 3.9 ≤ 7.9 and 4.0 ≤ 8.3, respectively, with over 80% of all the data having values ranging between 5 and 10 m/s or more. Most probable and maximum energy-carrying wind speeds also were found to be between 3.7 and 7.7 m/s and 4.5 and 9.3 m/s, respectively, across the period. Estimated wind power densities also ranged from 69.0 (in October) to 626.2 W/m2 (in January) at 10 m height. Seasonally, the dry season experiences higher wind speeds and the period of highest wind energy harvest could be from January to June every year

Diurnal Variation of TEC and S 4 Index During the Period of Low Geomagnetic Activity at Ile-Ife, Nigeria

Ile-Ife lies on the equatorial anomaly region where the ionospheric current is greatly influenced by the existence of the equatorial electrojet. The dual frequency SCINDA NovAtel GSV 4004B GPS receiver recently installed at Ile-Ife [on geographical latitude 7°33′N and longitude 4°33′E and geomagnetic dipole (coordinate) of latitude 9.84°N and longitude 77.25°E] is currently operational and recording data from the available global positioning system satellites. The receiver provides the data on total electron content (TEC) and the scintillation index (S[subscript 4]). This paper presents the first sets of results from this station. Data records for the month of February 2010 were analyzed using the WinTec-P software program and these were interpreted to discuss the diurnal variation of the TEC and S[subscript 4] index during the period considered, as having low geomagnetic activity. The vertical TEC in this study showed that the values vary widely from as low as 0 TECu about sunrise to about 35 TECu during the day. Depletion in TEC was also noticed about sunset and marked by the occurrence of scintillations with a maximum index value of 0.3. Results of the IRI models and the observed TEC differ considerably; hence, there is the need to improve IRI models for its adaptability to the Africa ionospheric conditions