Potassium doping of sputtered MoS2 films by CVD method

Doping is an essential approach to enhance the electrical properties of 2D materials. In the present study, two-stage process was used to obtain potassium-doped (K-doped) MoS2. The MoS2 films were grown by magnetron sputtering technique and followed by doping process employing CVD method. The influence of KOH molarity and annealing time on the structural properties of the MoS2 films was investigated thoroughly. 0.2-0.8-M KOH was used to obtain K-doped MoS2. The increase in the molarity of KOH caused a shift in the optical band gap from 1.98 to 1.81 eV. It was observed that increasing the KOH molarity resulted in the loss of homogeneity in the MoS2 films, the use of 0.2-M KOH for the growth of K-doped MoS2 exhibited the most promising results according to performed analyzes. In addition, annealing time also played a critical role in the growth of K-doped MoS2. The dwell times of 5, 10, and 15 min were also used and the effect of molarity and dwell times was investigated. The optical band gap was also shifted from 1.9 to 1.71 eV with increasing the dwell time of KOH. Longer annealing times resulted in the deterioration of the MoS2 film structure. Consequently, an annealing time of 5 min was found to be the optimum value for the growth of K-doped MoS2 film. Overall, this study demonstrates that successful growth of high-quality and homogeneous K-doped MoS2 films which can be employed for various optoelectronic applications.