Evolution of the Thermal Conductivity of MoS₂ Induced by Swift-heavy Ion Irradiation

Molybdenum disulphide (MoS₂) was irradiated by 0.97 GeV ²⁰⁹Bi ions with the fluence of 1×10¹⁰ to 1×10¹² ions/cm². The irradiation effect on the thermal conductivity of MoS₂ was analyzed by atomic force microscope (AFM) and Raman spectroscopy. The experimental results show that hillock-like latent tracks are observed on irradiated MoS₂ by AFM. The measurement of MoS₂ by Raman spectrometer with high laser power results in the increase of local temperature of MoS₂, which cause the downshift of peaks position and broadening of E_1/2g and A_1g peak. Furthermore, according to Raman spectra measured at different laser power, thermal conductivity of MoS₂ before and after irradiation was calculated, which show that the thermal conductivity of MoS₂ decreases with increasing fluence, from 563 to 132 W/mK for pristine and 1×10¹² ions/cm² irradiated MoS₂, respectively.