Yuanyuan Jin,Jian Sun,Ling Zhang,Junqiang Yang,Yangwu Wu,Bingying You,Xiao Liu,Kai Leng,Song Liu
High-κ materials that exhibit large permittivity and band gaps are needed as gate dielectrics to enhance capacitance and prevent leakage current in downsized technology nodes. Among these, monoclinic ZrO 2 (m-ZrO 2 ) shows good potential because of its inertness and high-κ with respect to SiO 2 , but a method to produce ultrathin single crystal is lacking. Here, the controllable preparation of ultrathin m-ZrO 2 single crystals via the in situ thermal oxidation of ZrS 2 is achieved. As-grown m-ZrO 2 presents an equivalent oxide thickness of ≈0.29 nm, a high dielectric constant of ≈19, and a breakdown voltage ( E BD ) of ≈7.22 MV cm −1 . MoS 2 field effect transistor (FET) by using m-ZrO 2 as a dielectric layer shows comparable mobility to that using SiO 2 dielectric. The ultraclean interface of m-ZrO 2 /MoS 2 and high crystalline quality of m-ZrO 2 lead to negligible hysteresis in transfer curves. Single crystal m-ZrO 2 dielectric shows potential application in digital complementary metal oxidesemiconductor (CMOS) logic FET.
Group-IVB transition metal dichalcogenides such as HfS2 and ZrS2 demonstrate the most promising the semiconducting properties, with moderate band gaps and high predicted carrier mobilities. However, lateral growth of large domain-size single crystalline ZrS2 nanosheets still lack to be developed, which limited various electronic and optoelectronic applications. Here, we report a new precursor strategy for the synthesis of large-sized 2D ZrS2 nanosheets with lateral orientations. The stable precursor volatilization of high melting point zirconium carbide was controlled by the assistance of remote gas-phase alkali halide, which avoid the high nucleation density and vertical orientation at the initial stage. The 2D ZrS2 nanosheets were regulated by adjusting the growth parameters with the lateral size up to 22 μm and thinnest thickness of 8 nm, exhibiting high crystalline qualities and uniform surface. Field effect transistors of 2D ZrS2 nanosheets exhibited n-type transport characteristics with high on/off ratio and reasonable carrier mobilities. Our new precursor and chemical design pave a way for the synthesis of high-performance Group-IVB transition metal dichalcogenides wafers.
Zhi Li,Zhengyang Zhou,Jiawei Zhang,Chenxi Zhu,Pengfei Qiu,Tingting Deng,Fangfang Xu,Lidong Chen,Xun Shi
Materials with low thermal conductivity have received significant attention across various research fields, including thermal insulation materials, thermal barrier coatings, and thermoelectric materials. Exploring novel materials with intrinsically low thermal conductivity and investigating their phonon transport properties, chemical bonding, and atomic coordination are crucial. In this study, a novel ternary sulfide is successfully discovered, Cu 2 ZrS 3 , which is achieved by introducing copper ions into both the interlayer and intralayer of ZrS 2 . The resulting structure encompasses various coordination forms within each layer, such as [CuS 4 ], [ZrS 6 ], and [CuS 3 ], leading to pronounced phonon anharmonicity induced by the asymmetric bonding of tri-coordinated Cu atoms within the [ZrS 6 ] layer. As a result, Cu 2 ZrS 3 exhibits intrinsically low lattice thermal conductivity ( κ L ) of about 0.83 W m −1 K −1 at 300 K and 0.35 W m −1 K −1 at 683 K, which are in the exceptionally low level among sulfides. In comparison to the conventional approach of inserting guests between layers, the substitution of atoms within layers provides a novel and effective strategy for designing low κ L materials in transition metal dichalcogenides (TMDCs).
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