Observation of persistent photoconductivity in Ni-doped MoS2

In this study, Ni-doped MoS2 was grown by chemical vapor transportation. Photoconductivity results reveal that Ni-doped MoS2 has an obvious doping level of 1.2 eV and an electrical conductivity of sigma congruent to 9.92 x 10(-7) S cm(-1) at room temperature, which is lower than that of undoped MoS2 (sigma congruent to 7.913 x 10(-5) S cm(-1)) owing to the impurity state caused by Ni atoms. Hall effect measurement results indicate that Ni-doped MoS2 sample is of the n-type and has a higher resistance and a lower mobility than undoped MoS2. We further fabricated undoped and Ni-doped MoS2 photodetectors to understand the operation characteristics of MoS2-based photodetectors. Persistent photoconductivity shows that both rise and fall times decreased from 0.33/0.68 to 0.14/0.43 s as Ni atoms were doped in MoS2 PDs. This work shows that Ni atoms could cause small lattice imperfections to form trap states leading to high resistance, low mobility, small activation energy and short decay time. Therefore, doping Ni atoms in MoS2 is beneficial for the application of photodetectors. (C) 2017 The Japan Society of Applied Physics