We report on the chemical vapor deposition (CVD) growth of quasi-one-dimensional zirconium tritelluride (ZrTe3) at temperatures below 600 degrees C and process times under an hour, which results in a material on a SiO2/Si wafer substrate that offers electrical conductivity comparable to the bulk. This study combines tailored CVD processing using a tube-in-a-tube technique with characterization by optical microscopy, Raman spectroscopy, and scanning electron microscopy. Transmission electron microscopy validates the composition and offers atomic contrast. Electrical transport measurements employ an yttrium-gold stack to achieve good adhesion and low contact resistance. A positive temperature coefficient is observed, as expected for a metallic material. The obtained results are important for the proposed applications of quasi-one-dimensional van der Waals materials in the next-generation electronic devices.
Low turn-on (knee) voltage (∼0.3 V) Schottky-diode behavior of a four-layer (4L) MoS2/GaN junction is achieved by optimizing the in situ interface preparation of the GaN substrate prior to MoS2 overlayer growth in a vacuum system using metallic molybdenum and hydrogen sulfide gas as precursors. The process leads to a clean nitrogen-terminated GaN surface that bonds well to the MoS2 film revealing a 2 × 2 reconstruction at the interface observed in low-energy electron diffraction (LEED). Atomic force microscopy and X-ray photoelectron spectroscopy provide clear images of the GaN terraces through the MoS2 overlayer confirming close adhesion and absence of oxygen and other contaminants. Density functional theory calculations predict the formation of the 2 × 2 superstructure at a clean interface. Transport measurements show diode behavior at an on/off ratio of ∼105 for ±1 V with a forward direction for the positive voltage applied to the MoS2 layer. Combining transport and photoelectron spectroscopy measurements with theory, we deduce a Fermi-level position in the MoS2 gap consistent with interface charge transfer from MoS2 to the substrate. The high performance of the MoS2/Gan diode highlights the technological potential of devices based on GaN/MoS2 interfaces.