National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Enantioselective synthesis. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Temperature Dependent Phonon Shifts in Single-Layer WS2

Abstract: Atomically thin two-dimensional tungsten disulfide (WS2) sheets have attracted much attention due to their potential for future nanoelectronic device applications. We report first experimental investigation on temperature dependent Raman spectra of single-layer WS2 prepared using micromechanical exfoliation. Our temperature dependent Raman spectroscopy results shows that the E12g and A1g modes of single-layer WS2 soften as temperature increases from 77 to 623 K. The calculated temperature coefficients of the frequencies of 2LA(M), E12g, A1g, and A1g(M) + LA(M) modes of single-layer WS2 were observed to be −0.008, −0.006, −0.006, and −0.01 cm–1 K–1, respectively. The results were explained in terms of a double resonance process which is active in atomically thin nanosheet. This process can also be largely applicable in other emerging single-layer materials.

Photoconductive CdS Films by a Chemical Bath Deposition Process

Abstract: A new technique for the preparation of CdS thin films by chemical bath deposition is described. The CdS films prepared by this method have many of the advantages of those made by the spray deposition method, such as the ease of coating large areas and simplicity of the process. The stoichiometry is easy to maintain in both these methods. The films are formed on rotating substrates from a bath containing cadmium salt in a complex form. Electrical, photoconducting, and optical properties such as I--V characteristics, decay of photoconductivity, spectral response of photoconductivity, and optical absorption were studied. Addition of cations like Ag, Cu. In, and Zn to the deposition bath makes the films amorphous. Such amorphous layers have a density of state of the order of 10/sup 19/--10/sup 20//cm/sup 3//eV near the Fermi level, as determined by photodecay and field effect measurements. The films produced are strong, adhering tightly to the substrates, show little or no degradation, and are photosensitive as deposited.