Al-free and Al-doped V₂O₅ nanostructures were synthesized by a thermal-chemical vapor deposition (CVD) process on Si(100) at 850 °C under 1.2 × 10⁻¹ Torr via a vapor-solid (V-S) mechanism. X-ray diffraction (XRD), Raman, and high-resolution transmission electron microscopy (HRTEM) confirmed a typical orthorhombic V₂O₅ with the growth direction along [110]-direction of both nanostructures. Metallic Al, rather than Al³⁺-ion, was detected by X-ray photoelectron spectroscopy (XPS), affected the V₂O₅ crystallinity. The photoluminescence intensity of V₂O₅ nanostructure at 1.77 and 1.94 eV decreased with the increasing Al-dopant by about 61.6% and 59.9%, attributing to the metallic Al intercalated between the V₂O₅-layers and/or filled in the oxygen vacancies, which behaved as electron sinks. Thus the Al-doped V₂O₅ nanostructure shows the potential applications in smart windows and the electrodic material in a Li-ion battery.

ZnO/carbon-black heterostructures were synthesized using a sol–gel method and crystallized by annealing at 500 °C under 2 × 10⁻² Torr for 10 min. The crystal structures and binding vibration modes were determined by XRD, HRTEM, and Raman spectrometry. Their surface morphologies were observed by FESEM. The Moiré pattern that is observed in the HRTEM images confirms that the carbon-black nanoparticles were covered by the ZnO crystals. Measurements of optical absorptance revealed that the optical band gap of the ZnO/carbon-black heterostructures increased from 2.33 to 2.98 eV as the carbon-black nanoparticle content increases from 0 to 8.33 × 10⁻³ mol owing to the Burstein–Moss effect. The photoluminescence intensities at the near-band edge and of the violet, and blue light were increased by factors about 68.3, 62.8, and 56.8, respectively, when the carbon-black contents is of the 2.03 × 10⁻³ mol. This work reveals that the proper carbon-black nanoparticle content involved increases the PL intensities of the ZnO crystals in the short wavelength regime, supporting their potential application in the light-emitting devices.

Pristine, and In-, Sn-, and (In, Sn)-doped Bi₂Se₃ nanoplatelets synthesized on Al₂O₃(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10⁻² Torr. XRD and HRTEM reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-Bi₂Se₃. FPA–FTIR reveals that the optical bandgap of doped Bi₂Se₃ was 26.3%, 34.1%, and 43.7% lower than pristine Bi₂Se₃. XRD, FESEM–EDS, Raman spectroscopy, and XPS confirm defects ($I{n}^{3+}{}_{B{i}^{3+}}$), ($I{n}^{3+}{}_{V^0}$), ($S{n}^{4+}{}_{B{i}^{3+}}$), ($V^0{}_{B{i}^{3+}}$), and ($S{n}^{2+}{}_{B{i}^{3+}}$). Photocurrent that was generated in (In,Sn)-doped Bi₂Se₃ under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10⁻¹⁰ and 0.35 × 10⁻¹⁰ A and high I_photo/I_dark ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10⁻² and 6.6 × 10⁻² s. Under UV light, (In,Sn)-dopedBi₂Se₃ had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine Bi₂Se₃, indicating that (In,Sn)-doped Bi₂Se₃ exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine Bi₂Se₃ under UV and red light. The findings also suggest that type of defect is a more important factor than optical bandgap in determining photo-detection sensitivity. (In,Sn)-doped Bi₂Se₃ has greater potential than undoped Bi₂Se₃ for use in UV and red-light photodetectors.

Bi₂Se₃ is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. In this work, Ag@Bi₂Se₃ nanoplatelets were synthesized on Al₂O₃(100) substrates in a two-step process of thermal evaporation and magnetron sputtering. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) revealed that all samples had the typical rhombohedral Bi₂Se₃. Field-emission scanning electron microscopy (FESEM)-energy dispersive x-ray spectroscopy (EDS), XPS, and HRTEM confirmed the presence of the precipitated Ag. The optical absorptance of Bi₂Se₃ nanoplatelets in UV-visible range decreased with the Ag contents. Results of photocurrent measurements under zero-bias conditions revealed that the deposited Ag affected photosensitivity. A total of 7.1 at.% Ag was associated with approximately 4.25 and 4.57 times higher photocurrents under UV and visible light, respectively, than 0 at.% Ag. The photocurrent in Bi₂Se₃ at 7.1 at.% Ag under visible light was 1.72-folds of that under UV light. This enhanced photocurrent is attributable to the narrow bandgap (~0.35 eV) of Bi₂Se₃ nanoplatelets, the Schottky field at the interface between Ag and Bi₂Se₃, the surface plasmon resonance that is caused by Ag, and the highly conductive surface that is formed from Ag and Bi₂Se₃. This work suggests that the appropriate Ag deposition enhances the photocurrent in, and increases the photosensitivity of, Bi₂Se₃ nanoplatelets under UV and visible light.

Amorphous indium tin zinc oxide (a-ITZO)/Bi₂Se₃ nanoplatelets (NPs) were fabricated using a two-step procedure. First, Bi₂Se₃ NPs were synthesized through thermal chemical vapor deposition at 600 °C on a glass substrate, and then a-ITZO was deposited on the surface of the Bi₂Se₃ NPs via magnetron sputtering at room-temperature. The crystal structures of the a-ITZO/Bi₂Se₃ NPs were determined via X-ray diffraction spectroscopy and high-resolution transmission electron microscopy. The elemental vibration modes and binding energies were measured using Raman spectroscopy and X-ray photoelectron spectroscopy. The morphologies were examined using field-emission scanning electron microscopy. The electrical properties of the a-ITZO/Bi₂Se₃ NPs were evaluated using Hall effect measurements. The bulk carrier concentration of a-ITZO was not affected by the heterostructure with Bi₂Se₃. In the case of the Bi₂Se₃ heterostructure, the carrier mobility and conductivity of a-ITZO were increased by 263.6% and 281.4%, respectively, whereas the resistivity of a-ITZO was reduced by 73.57%. This indicates that Bi₂Se₃ significantly improves the electrical properties of a-ITZO through its heterostructure, expanding its potential applications in electronic and thermoelectric devices.