Synthesis of Vertical MoO₂/MoS₂ Core–Shell Structures on an Amorphous Substrate via Chemical Vapor Deposition

Vertical MoO₂/MoS₂ core–shell structures were synthesized on an amorphous surface (SiO₂) by chemical vapor deposition at a high heating rate using a configuration in which the vapor phase was confined. The confined reaction configuration was achieved by partially covering the MoO₃-containing boat with a substrate, which allowed rapid buildup of the partially reduced MoO_3–<i>x</i> crystals in an early stage (below 680 °C). Rapid temperature ramping to 780 °C enabled spontaneous transition of the reaction environment from sulfur-poor to sulfur-rich, which induced a sequential phase transition from MoO_3–<i>x</i> to intermediate MoO₂ and finally to MoO₂/MoS₂ core–shell structures. The orthorhombic crystal structure of MoO_3–<i>x</i> contributed to the formation of vertical crystals on the amorphous substrate, whereas the nonvolatility of the subsequently formed MoO₂ enabled layer-by-layer sulfurization to form MoS₂ on the oxide surface with minimal resublimation loss of MoO₂. By adjustment of the sulfurization temperature and time, excellent control over the thickness of the MoS₂ shell was achieved through the proposed synthesis method

Chemically Homogeneous and Thermally Robust Ni_1–<i>x</i>Pt_<i>x</i>Si Film Formed Under a Non-Equilibrium Melting/Quenching Condition

To synthesize a thermally robust Ni_1–<i>x</i>Pt_<i>x</i>Si film suitable for ultrashallow junctions in advanced metal-oxide-semiconductor field-effect transistors, we used a continuous laser beam to carry out millisecond annealing (MSA) on a preformed Ni-rich silicide film at a local surface temperature above 1000 °C while heating the substrate to initiate a phase transition. The melting and quenching process by this unique high-temperature MSA process formed a Ni_1–<i>x</i>Pt_<i>x</i>Si film with homogeneous Pt distribution across the entire film thickness. After additional substantial thermal treatment up to 800 °C, the noble Ni_1–<i>x</i>Pt_<i>x</i>Si film maintained a low-resistive phase without agglomeration and even exhibited interface flattening with the underlying Si substrate