Electrical and optical anisotropic properties of rhenium-doped molybdenum disulphide

Single crystals of rhenium (Re)-doped MoS2 have been grown by chemical vapor transport method using bromine os a transport agent. Single crystalline platelets up to 10X10 mm(2) surface area and 2 mm in thickness Mr 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 MoS2 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 MoS2 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 asis show different degrees of red shift in comparing with the features perpendicular to c axis anil with that of the undoped sample. The role of rhenium in affecting both the electrical and optical properties of the MoS2 crystals is examined. (C) 2001 Elsevier Science B.V. All rights reserved.