Structural and Optical Characterization of Tungsten Diselenide Crystals Grown by DVT Technique

Abstract

WSe2 is a member of groupVI Transition Metal Dichalcogenides (TMDCs) and has been observed to be a highly stable semiconducting material. It has been grown in crystal form using a direct vapour transport technique in present case. The grown WSe2 crystals were characterized for the structural properties using X-ray diffraction technique (XRD). The hexagonal structure was confirmed through this analysis. Using the data of XRD, various parameters like crystalline size, lattice parameters, micro strain, dislocation density, unit cell volume, unit cell density, growth fault and deformation fault probability etc were found. It was seen that the micro strain, dislocation density and growth & deformation fault probabilities were found to be very low in WSe2 crystals. The grown WSe2 crystals were characterized for optical properties using UV-VIS-NIR spectroscopy. The absorption spectra of WSe2 grown in present case revealed the fact that WSe2 posses direct band gap around 1.38eV. Layered di-chalcogenides WSe2 (or MoSe2) are used for desired applications such as in photo-conversion devices.