Fig. 1. (Color online) (a) Schematic diagram of two-dimensional ZrO₂ nanosheets prepared by one-step CVD. The lower part shows the formation of m-ZrO₂ at the atomic level. (b) Optical image of ZrO₂ grown on a silicon substrate. Scale bar: 20 μm. (c) Raman spectra of m-ZrO₂ nanosheets. (d) SEM image of ZrO₂ nanosheet at 18 000x magnification. Scale bar: 1 μm. (e) AFM image and corresponding height maps of ZrO₂ nanosheets. Scale bar: 1 μm.

Fig. 2. (Color online) (a) XRD spectra of ZrO₂ nanosheets. (b) XPS broad spectra of ZrO₂ nanosheets. (c) XPS narrow spectra of Zr 3d. (d) XPS narrow spectra of O 1s.

Fig. 3. (Color online) (a) TEM. Scale bar: 500 nm. (b) HRTEM. Scale bar: 2 nm. (c) SEAD. Scale bar: 2 nm⁻¹. (d) EDS of ZrO₂ nanosheets.

Fig. 4. (Color online) (a) Optical image and (b) Raman spectra of ZrS₂ without the introduction of 5A molecular sieves. Scale bar: 10 μm. (c) Optical image and (d) Raman spectra of ZrO₂ with the incorporation of 5A molecular sieves. Scale bar: 30 μm. (e) Optical images of ZrO₂ grown on the SiO₂/Si substrate at different deposition temperatures (780/830/880 °C). Scale bar: 20 μm.

Fig. 5. (Color online) (a) The schematic of MoS₂−ZrO₂ heterojunction FET. (b) Optical picture of the prepared FET, with the corresponding AFM image in the upper left corner. Scale bar: 10 μm. (c) Output characteristic curve of FET. (d) Transfer characteristic curve of FET.