Fig. 1. Preparation processes of the bulk SnSe₂.

Fig. 2. (a) XRD patterns of SnSe₂, the inset is the crystal structure of the SnSe₂; (b) and (c) FESEM images of the fresh fracture surface of SnSe₂ after SPS synthesis; (d) EDS spectrum of SnSe₂; (e) the Se elemental map and (f) the Sn elemental map.

Fig. 3. Temperature dependence (10−300 K) of the resistivity (a) and carrier concentration and mobility (b).

Fig. 4. (a) V-I characteristic curves of SnSe₂ with current sweep as –100 mA → 0 → 100 mA → 0 → –100 mA for 3 times at 300 K, the inset shows the schematic of the device; (b) V-I characteristic curves of SnSe₂ with current sweep as –100 mA → 0 → 100 mA → 0 → –100 mA for 3 times at 10 K.

Fig. 5. (a) V-I characteristic curves of SnSe₂ in current sweep as 0 mA → 100 mA → 0 mA at ambient temperature 285 K, the inset shows the ultrared detection diagram of the device directly exchanging heat with air; (b) temperature distribution maps of the sample at temperature points A, B and C in (a); (c) the DSC curves of SnSe₂.

Fig. 6. lgV-lgI curves in negative bias region (a) and positive bias region (b) at 300 K, respectively; lgV-lgI curves in in negative bias region (c) and positive bias region (d) at 10 K, respectively.

Fig. 7. V-I characteristic curves under different magnetic fields at 300 K (a), 200 K (c), 100 K (e) and 10 K (g), respectively; lgV-lgI characteristic curves under different magnetic fields at 300 K (b), 200 K (d), 100 K (f) and 10 K (h), respectively. The insets in (b) and (d) show the magnified parts of curves.

Fig. 8. (a) Electron motion process dominated by lattice scattering; (b) influence of magnetic field on the electron motion process dominated by lattice scattering; (c) electron localization process dominated by impurity scattering; (d) influence of magnetic field on the electron localization process dominated by impurity scattering.

Fig. 9. (a) MR-B curves in different regions at 100 K; (b) MR-B curves in different regions at 10 K.