Electrical and optical anisotropic properties of rhenium-doped molybdenum disulphide

Abstract

Single crystals of rhenium (Re)-doped MoS 2 have been grown by chemical vapor transport method using bromine as a transport agent. Single crystalline platelets up to 10×10 mm 2 surface area and 2 mm in thickness are obtained. By analyzing the X-ray diffraction profile, the structure of the single crystals shows rhombohedral symmetry. The Hall measurements indicate that the samples are n-type in nature. The thicker Re-doped MoS 2 samples enable easier exploration of the electrical and optical anisotropies of the materials both parallel and perpendicular to the c axis of the crystals. The anisotropy of electrical conductivity perpendicular to and along the c axis for the Re-doped MoS 2 is about 10 2 and is at least one order smaller than 10 3 for the undoped samples. The optical anisotropic property was studied using electrolyte electroreflectance measurements. The excitonic transitions of A and B features parallel to c axis show different degrees of red shift in comparing with the features perpendicular to c axis and with that of the undoped sample. The role of rhenium in affecting both the electrical and optical properties of the MoS 2 crystals is examined.