Fig. 1. A sketch map of experiment process.

Fig. 2. Plan-view TEM images of MoS₂ after swift heavy ion irradiation with (a), (b) ¹²⁹Xe 5×10¹² ions/cm², (c), (d) ¹⁸¹Ta 5×10¹⁰ ions/cm², and (e), (f) ²⁰⁹Bi 5×10¹¹ ions/cm². The left and right rows are the phase contrast images obtained at under-focus and over-focus conditions, respectively.

Fig. 3. Statistical diameter distribution of ion tracks in irradiated MoS₂ with different electronic energy losses. The average diameters of the ion tracks (D_a) are fitted according to Gaussian curve.

Fig. 4. TEM images of different ion track morphologies of MoS₂ irradiated at 30° with 1785.7 MeV ¹⁸¹Ta ions. (a) Nearly cylindrical ion tracks consist of two spherical hillocks at each end. (b) Sandglass-like ion tracks. The apparent length in MoS₂ sample is about 180 nm. (c) The q-tips-like ion tracks. The size of hillocks increases with increasing apparent length.

Fig. 5. Schematics of the formation process of ion track in irradiated MoS₂ with SHIs. (a) SHIs bombardment. (b) Target material melting along the ion path. (c) Outflow of molten phase towards the free surface. (d) Recrystallization in ion damage zone.

Table 1. Irradiation parameters for MoS₂.

Table 2. Track related parameters of MoS₂ with different morphologies. Morphology, hillock diameter (D_h), apparent track length (L_ap), and actual track length (L_ac) were obtained from TEM measurements in Fig. 3.