Mahesh D. Chaudhary

SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

The SnS thin films were synthesized by chemical bath deposition (CBD), dip coating and successive ionic layer adsorption and reaction (SILAR) techniques. In them, the CBD thin films were deposited at two temperatures: ambient and 70 °C. The energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I–V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

Synthesis and characterization of different morphological SnS nanomaterials

SnS in three nano forms possessing different morphologies such as particles, whiskers and ribbons were synthesised by chemical route. The morphology variation was brought about in the chemical route synthesis by varying a synthesis parameter such as temperature and influencing the synthesis by use of surfactant. The elemental composition determination by energy dispersive analysis of x-rays (EDAX) showed that all three synthesized SnS nanomaterials were tin deficient. The x-ray diffraction (XRD) study of the three SnS nanomaterials showed that all of them possess orthorhombic structure. The Raman spectra of the three SnS nanomaterials showed that all three samples possess three common distinguishable peaks. In them two peaks lying at 98 ± 1 cm−1 and 224 ± 4 cm−1 are the characteristic Ag mode of SnS. The third peak lying at 302 ± 1 cm−1 is associated with secondary Sn2S3 phase. The transmission electron microscopy (TEM) confirmed the respective morphologies. The optical analysis showed that they possess direct as well as indirect optical bandgap. The electrical transport properties study on the pellets prepared from the different nanomaterials of SnS showed them to be semiconducting and p-type in nature. The current–voltage (I–V) plots of the silver (Ag)/SnS nanomaterials pellets for dark and incandescent illumination showed that all configurations showed good ohmic behaviour except Ag/SnS nanoribbons pellet configuration under illumination. All the obtained results are discussed in detail.

Effect of Indium and Antimony Doping on SnS Photoelectrochemical Solar Cells

Single crystals of pure SnS, indium (In) and antimony (Sb) doped SnS are grown by the direct vapor transport technique. Two doping concentrations of 5at.% and 15 at.% are employed for both In and Sb dopants. In total, five samples are studied, i.e., pure SnS, 5at.% In-doped SnS, 15 at.% In-doped SnS, 5at.% Sb-doped SnS and 15 at.% Sb-doped SnS single crystals. The energy dispersive analysis of x-ray (EDAX) and x-ray diffraction (XRD) analysis show that all the five as-grown single crystal samples possess near perfect stoichiometry and orthorhombic structure, respectively. The doping of In and Sb in SnS is established from the EDAX data and from the shift in the peak positions in XRD. Photoelectrochemical (PEC) solar cells are fabricated by using the as-grown single crystal samples along with iodine/iodide electrolytes. Mott—Schottky plots for different compositions of iodine/iodide electrolytes show that 0.025M I2+1M NaI+2M Na2SO4+0.5M H2SO4 will be the most suitable electrolyte. Study of efficiency (η) and fill factor for different intensities of illuminations at room temperature is carried out for the five samples. The In-doped SnS single crystals show better PEC efficiency than the undoped and Sb-doped SnS single crystals.

Synthesis and electrical transport properties of SnS nanoparticles

The SnS nanoparticles were synthesized at ambient temperature by simple wet chemical method. The stoichiometric and structural characterization was done by EDAX and XRD techniques respectively. The crystallite size was determined using Scherrers formula and Hall-Williamson plot using XRD data. The electrical transport properties studies were carried out on pellets prepared by hydraulic pressing of SnS nanoparticles. The thermoelectric power and dc resistivity variation with temperature was studied on the pellets. Room temperature Hall effect measurement was made on the pellet. The obtained results are discussed in details.

Study of surface microstructure and optical properties of as-grown Mo0.6W0.4Se2 single crystals

The surface microstructures and optical properties of as-grown Mo0.6W0.4Se2 single crystals were studied. The microstructures on the as-grown crystal surface reveals that spirals and Frank-Read dislocations are prominent. The study of the variation of refractive index (η), extinction coefficient (k), real and imaginary dielectric constants (er and ei), and the optical conductivity (σ0) with incident photon energy from the analysis of optical absorption spectrum of Mo0.6W0.4Se2 single crystals, showed that near the bandgap energy value all sharply increases.

Synthesis and thermal study of SnS nanoflakes

Abstract SnS nanoflakes were synthesized by chemical route at a temperature of 80 °C. Stannous chloride and sodium sulphide was used as a source of Sn2+ and S2− ions respectively. The elemental stoichiometric analysis of SnS nanoflakes was done by employing energy dispersive analysis of X-rays (EDAX) technique. The structural study of the as-synthesized nanoflakes was studied by X-ray diffraction (XRD). The grain size was determined using X-ray diffraction (XRD) data employing Scherrer’s formula and Hall–Williamson plot. The residual strain produced in the synthesized nanoflakes during the synthesis was obtained from Hall–Williamson plot. The transmission electron microscopy (TEM) image showed that the synthesized nanoflakes have average crystallite size of 11 nm. The thermal decomposition of SnS nanoflakes was studied employing thermogravimetric (TG), differential thermogravimetric (DTG) and differential thermal analysis (DTA) techniques. The thermal behaviour of SnS nanoflakes was compared with SnS single crystals. The thermal parameters were evaluated of the SnS nanoflakes using two most common thermal analysis methods; Broido and Coats-Redfern (CR) relations. Thermal activation energy, enthalpy change (ΔH*), entropy change (ΔS*) and free energy change (ΔG*) related to the thermal decomposition process were calculated for the SnS nanoflakes. The obtained results are discussed in details.

Electrical transport properties study of Mo0.6W0.4Se2 single crystals

The mixed transition metal dichalcogenide single crystals Mo0.6W0.4Se2 were characterized employing EDAX (Energy Dispersive Analysis of X-ray), (XRD) X-ray diffraction, SEM (Scanning Electron Microscope) and UV-Vis-NIR spectroscopy techniques. The electrical transport properties of as-grown Mo0.6W0.4Se2 single crystals were studied by two probe d. c. resistivity, Hall Effect and thermoelectric power measurement set-up. The obtained results are discussed in details.