Electrical and optical properties of Co-doped and undoped MoS2

Abstract Co-doped and undoped layered MoS 2 crystals were grown by the chemical vapor transport method using iodine as the transport agent. Both reflectance and piezoreflectance measurements reveal two exciton transitions of the direct band edge around 1.86 and 2.06 eV for undoped MoS 2 and 1.84 and 2.03 eV for Co-doped MoS 2 . Hall effect measurements show that the Co-doped MoS 2 sample has a lower carrier concentration and mobility than the undoped sample. These differences between undoped and Co-doped MoS 2 were attributed to the effect of cobalt atoms causing a small lattice distortion, lattice imperfections and/or impurity states that form trap states between the conduction band and valence band. Furthermore, photoconductivity (PC) and persistent PC results show that Co-doped MoS 2 has a longer time constant and better responsivity than undoped MoS 2 . This work discusses the advantages of Co-doped MoS 2 for photodetector applications.