We report on the phonon and thermal properties of thin films of tantalum diselenide (2H-TaSe2) obtained via the “graphene-like” mechanical exfoliation of crystals grown by chemical vapor transport. The ratio of the intensities of the Raman peak from the Si substrate and the E2g peak of TaSe2 presents a convenient metric for quantifying film thickness. The temperature coefficients for two main Raman peaks, A1g and E2g, are −0.013 and −0.0097 cm−1/oC, respectively. The Raman optothermal measurements indicate that the room temperature thermal conductivity in these films decreases from its bulk value of ∼16 W/mK to ∼9 W/mK in 45-nm thick films. The measurement of electrical resistivity of the field-effect devices with TaSe2 channels shows that heat conduction is dominated by acoustic phonons in these van der Waals films. The scaling of thermal conductivity with the film thickness suggests that the phonon scattering from the film boundaries is substantial despite the sharp interfaces of the mechanically cleaved samples. These results are important for understanding the thermal properties of thin films exfoliated from TaSe2 and other metal dichalcogenides, as well as for evaluating self-heating effects in devices made from such materials.

Quasi-1D van der Waals materials, such as transition metal trichalcogenides, have strong covalent bonds in one direction and weaker bonds in crossplane directions. They can be prepared as crystalline nanowires or nanoribbons consisting of 1D atomic threads, i.e., chains. We have examined the current carrying capacity of ZrTe ₃ nanoribbons using a set of structures fabricated by the shadow mask method. The bulk crystals were synthesized by the chemical vapor transport method and exfoliated onto Si/SiO ₂ substrates. It was found that ZrTe ₃ nanoribbons reveal an exceptionally high current density, on the order of ~100 MA/cm ₂ , at the peak of the stressing DC current. The low-frequency noise was of 1/f type near room temperature (f is the frequency). The noise amplitude scaled with the resistance, following the trend established for other low-dimensionalmaterials. The high current density in ZrTe ₃ can be attributed to the single-crystalnature of quasi-1D van der Waals materials.

The $1{T}$ polytype of TaS₂ exhibits voltage-triggered threshold switching as a result of a phase transition from nearly commensurate to incommensurate charge density wave states. Threshold switching, persistent above room temperature, can be utilized in a variety of electronic devices, e.g., voltage controlled oscillators. We evaluated the total-ionizing-dose response of thin film $1{T}$ -TaS₂ at doses up to 1 Mrad (SiO₂). The threshold voltage changed by less than 2% after irradiation, with persistent self-sustained oscillations observed through the full irradiation sequence. The radiation hardness is attributed to the high intrinsic carrier concentration of $1{T}$ -TaS₂ in both of the phases that lead to threshold switching. These results suggest that charge density wave devices, implemented with thin films of $1{T}$ -TaS₂, are promising for applications in high radiation environments.