Growth and characterizations of tin telluride (SnTe) single crystals

In recent time, materials in two-dimensional (2D) forms have gained importance along with nano-forms both from the fundamental and the technological point of view. Amongst the vast compound semiconductors, tin telluride (SnTe) is a potential candidate to find interest in the 2D form. The single crystals in the 2D flake forms of SnTe are grown by vapour transport technique in direct mode within closed quartz ampoule geometry. The stoichiometry of as-grown crystals is confirmed by the energy-dispersive X-ray analysis, which showed that the as-grown SnTe single crystals to be near stoichiometric but slightly Te rich. The analysis by X-ray diffraction of as-grown SnTe single crystals confirmed the cubic structure having lattice parameters of a = b = c = 6.31 angstrom and alpha = beta = gamma = 90 degrees. The surface study is done by electron microscopy in scanning mode which shows bunching of layers one over other, near flat surface, and flower-like pattern on the edges of the crystals. The spot pattern observed in electron diffraction from selected area confirms the single-crystalline nature of crystals. The Raman spectrum of SnTe single crystal showed sharp peak at 132 cm(-1), attributed to transverse optical phonon vibration mode. The variation of d.c. electrical resistivity with temperature showed the SnTe single crystal to be metallic in nature and the value of bandgap is 0.19 eV. The thermal analysis of the as-grown SnTe single crystals is performed by recording the thermogravimetric, differential thermogravimetric, and differential thermal analysis curves. The kinetic parameters are derived by Kissinger method from the thermocurves data. The single crystals growth and varied characterization results on SnTe single crystals are thoroughly discussed.