Low thermal conductivity and high carrier mobility in type-II Dirac semimetal PtTe 2 thin films

High mobility is crucial for optoelectronic response and thermoelectric performance, while low thermal conductivity enhances the thermoelectric figure of merit (ZT) and reduces heat loss. PtTe2, a novel two-dimension (2D) Dirac semimetal, is a promising optoelectronic and thermoelectric material. Here, we characterize 2D PtTe2 films using transient thermal grating (TTG) and terahertz time-domain spectroscopy (THz-TDS). TTG reveals an extremely low thermal diffusion coefficient (~6.4 × 10−6 m2/s), much lower than most semiconductors and metals, likely from strong phonon−phonon scattering or phonon boundary scattering, with a corresponding thermal conductivity of ~10.4 W·m−1·K−1. THz-TDS shows excellent electrical transport: room-temperature conductivity reaches 4.7 × 105 S/m and carrier mobility is 1870 cm2·V−1·s−1, attributed to its highly ordered crystal and Dirac band structure. The ZT is 0.002 at room temperature, comparable to reported values for 2D thermoelectric materials. Combining low thermal conductivity and high mobility, 2D PtTe2 offers new opportunities for high-performance electronics and possible application in thermoelectrics.