AVS 69 Session EM-ThP: Electronic Materials and Photonics Poster Session

Tellurium (Te) has recently attracted substantial attention as a p-type channel material due to their favorable characteristics such as high transport properties, good photosensitivity, and piezoelectricity. Uniform and stable Te is important for the extensive applicability in terms of electronics and optoelectronics.Here, the novel hybrid channel of Te nanowires and Te-film for flexible p-type phototransistor arrays with highly linear photo-responsivity are reported for the first time. All the processes are conducted at a temperature lower than 100℃ to reduce thermal budget on a flexible substrate. This paper includes optical properties of the TeNWs/Te-based FETs such as threshold voltage shift, photocurrent, responsivity, sensitivity, and time-domain behavior as well as electrical performance of those devices. The array consisting of 50 devices exhibits high mobility of > 5 cm²V⁻¹s⁻¹ and I_on/I_off of > 10⁴on average. More significantly, the stability of the devices is confirmed by the various tests such as positive/negative bias stress, illumination added bias stress, long-term stability response, and even mechanical bending stress, which exhibits stable and uniform characteristics of the devices.

ZrSiS-type Lanthanide (Ln) based materials in the LnSbTe family bring the possibility of electronic correlations and magnetic ordering due to the presence of Ln 4f electrons in addition to the topology that the ZrSiS-type systems are well known for. Here, we carried out an angle-resolved photoemission spectroscopy (ARPES) study of Neodymium-based NdSbTe, supported by first-principles calculations and thermodynamic measurements. Thermodynamic measurements reveal a magnetic transition into an antiferromagnetic ground state at around 2 K. The paramagnetic phase ARPES results detect the presence of multiple gapless nodal lines, which is also supported by first-principles calculations. Two of such nodal lines reside along the bulk X-R high-symmetry direction and one lies across the Γ-M direction forming a diamond plane centered at the Γ point. Overall, this study reveals the topological electronic structure of NdSbTe and presents a new platform to understand how such electronic structure evolves with spin-orbit coupling tuning across the LnSbTe family.

*This work is supported by the National Science Foundation under CAREER Award No. DMR-1847962 and the Air Force Office of Scientific Research MURI Grant No. FA9550-20-1-0322.

Metallic 2D materials offer a unique pathway to aggressive thickness scaling without sacrificing resistivity. Unlike conventional metals which see significant increases in resistivity, when the thickness is on the order of the electron mean free path, due to increase surface/interface scattering, for 2D materials the conduction is already largely confined to the individual layers with negligible transport across the van der Waals gaps. As such, when scaled into the nm regime, these materials see little or no increase in their resistivity.

Niobium diselenide (NbSe₂) is a metal-like transition metal dichalcogenide that has a similar crystal structure to the well-studied 2H-MoS₂. In our work, NbSe₂ is grown by molecular beam epitaxy and is shown to naturally deposit with self-intercalated Nb in the van der Waals gap. We demonstrate how the resistivity of NbSe₂ varies as a function of deposition temperature and flux ratio and then turn our folks to how the oxidation behavior of the thin films. Specifically, we show that the grown temperature of the thin films impacts their subsequent stability in air, likely due to differing grain sizes. In addition to this we show that some processing steps that are typically nanoelectronic device fabrication can also oxidize the material which suggests that due consideration must be taken if this material is to be integrated into any device architectures.