Growth and characterization of WSe2 single crystals using TeCl4 as transport agent

• WSe2 single crystals (25–100 mm2) grown by the chemical vapor transport method.
• High quality single crystals obtained from slowly cooled polycrystalline powders.
• WSe2 single crystals with a photocurrent plateau at 75 mA cm−2.

The growth of WSe2 single crystals, using TeCl4 as transport agent was performed successfully from slowly cooled polycrystalline powders as precursors. The resulting single crystals were characterized by X-ray diffraction (XRD) and their surfaces examined by scanning electron microscopy (SEM) presented fewer defects than single crystals prepared from air-quenched polycrystalline powders. Energy Dispersive X-ray microanalysis (EDX), inductively coupled plasma (ICP) spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed that the single crystals are homogeneous and stoichiometric. Electrical conductivity and photocurrent measurements have confirmed the semiconducting character of the single crystals and a photocurrent of 75 mA cm−2 has been reached. In addition, single crystals with areas in the 25–100 mm2 range can be obtained under the reported growth conditions.