Remarkably fast and reusable photocatalysis by UV annealed Cu2O-SnO2 p-n heterojunction.

Powdered micro- or nano-particles photocatalyst has separation and recovery challenges, which may create a second pollution to environment and harmful to animals. To address those issues, SnO2, Cu2O and Cu2O-SnO2 p-n heterojunction thin films are formed on glass substrates using efficient co-sputtering method that is commonly employed for large-area high-definition display panel. Using first-order kinetics, 100 °C ultraviolet (UV) annealed Cu2O-SnO2 p-n heterojunction shows the superb fast degradation rate constant of 0.21 and 0.16 min-1 for methylene blue (MB) and methyl orange (MO) organic dyes, respectively, as photogenerated electron-hole pairs is increased. Record best degradation rate constants of 0.19 and 0.11 min-1 for respective MB and MO are still achieved even after four repeated cycles. The 100 °C UV annealed Cu2O-SnO2 film catalyst displays greater degradation efficiency in both dyes, reaching 100% degradation at room temperature after 30 and 35 min of illumination for MB and MO respectively. The scavenger experiments show that hydroxyl (·OH) and superoxide radicals (·O2-) are the major active species in the degradation of dye. The 100 °C UV annealed Cu2O-SnO2 film catalyst showed stability as well as reusability towards the dye degradation. As a result, the present work delivers an effective way to enhance the photocatalytic performance and also an easy recovery of the catalyst, which can be explored for various emerging pollutants.

Impact of UV annealing on the hole effective mobility in SnO pFET.

Using ultraviolet (UV) annealing through wide energy bandgap HfO2/SiO2 gate dielectric, nanosheet SnO pFET achieved hole effective mobility (µeff) from 55 cm2/V-s at low hole density (Qh) to 13.38 cm2/V-s at 5 × 1012 cm-2 Qh, compared to that of 9.03 cm2/V-s at 5 × 1012 cm-2 Qh for SnO device without UV annealing. This is the highest µeff among oxide semiconductor pFETs at high Qh, which is required to realize low-power high-density monolithic 3D CMOS logic. This requires excellent surface roughness, good uniformity and free-from grain boundaries that is beyond the thermally-annealed poly-Si. Excellent on-current/off-current (ION/IOFF) value of 1.05 × 105 were measured simultaneously in the UV-annealed SnO pFET, which is due to the ultra-thin 8 nm thick SnO nanosheet channel to pinch off the channel leakage. From X-ray photoelectron spectroscopy (XPS) analysis, the 48% µeff improvement by UV irradiation is due to increased Sn2+ and decreased Sn0. Such high µeff at high Qh, large ION/IOFF, smooth surface, good uniformity and low thermal budget process are the enabling technologies for monolithic 3D CMOS.

Superior High Transistor's Effective Mobility of 325 cm2/V-s by 5 nm Quasi-Two-Dimensional SnON nFET.

This work reports the first nanocrystalline SnON (7.6% nitrogen content) nanosheet n-type Field-Effect Transistor (nFET) with the transistor's effective mobility (µeff) as high as 357 and 325 cm2/V-s at electron density (Qe) of 5 × 1012 cm-2 and an ultra-thin body thickness (Tbody) of 7 nm and 5 nm, respectively. At the same Tbody and Qe, these µeff values are significantly higher than those of single-crystalline Si, InGaAs, thin-body Si-on-Insulator (SOI), two-dimensional (2D) MoS2 and WS2. The new discovery of a slower µeff decay rate at high Qe than that of the SiO2/bulk-Si universal curve was found, owing to a one order of magnitude lower effective field (Eeff) by more than 10 times higher dielectric constant (κ) in the channel material, which keeps the electron wave-function away from the gate-oxide/semiconductor interface and lowers the gate-oxide surface scattering. In addition, the high µeff is also due to the overlapped large radius s-orbitals, low 0.29 mo effective mass (me*) and low polar optical phonon scattering. SnON nFETs with record-breaking µeff and quasi-2D thickness enable a potential monolithic three-dimensional (3D) integrated circuit (IC) and embedded memory for 3D biological brain-mimicking structures.

The Recent Development in Chemoresistive-Based Heterostructure Gas Sensor Technology, Their Future Opportunities and Challenges: A Review.

Atmospheric pollution has become a critical problem for modern society; therefore, the research in this area continually aims to develop a high-performance gas sensor for health care and environmental safety. Researchers have made a significant contribution in this field by developing highly sensitive sensor-based novel selective materials. The aim of this article is to review recent developments and progress in the selective and sensitive detection of environmentally toxic gases. Different classifications of gas sensor devices are discussed based on their structure, the materials used, and their properties. The mechanisms of the sensing devices, identified by measuring the change in physical property using adsorption/desorption processes as well as chemical reactions on the gas-sensitive material surface, are also discussed. Additionally, the article presents a comprehensive review of the different morphologies and dimensions of mixed heterostructure, multilayered heterostructure, composite, core-shell, hollow heterostructure, and decorated heterostructure, which tune the gas-sensing properties towards hazardous gases. The article investigates in detail the growth and interface properties, concentrating on the material configurations that could be employed to prepare nanomaterials for commercial gas-sensing devices.

Annealing Effect of Glancing Angle Electron Beam Deposited TiO2/In2O3 Nanowires Array on Surface Wettability.

TiO2/In2O3 nanowire (NW) array are prepared using catalyst free glancing angle deposition technique. The wettability of TiO2/In2O3 NW surface are tuned and controlled by the annealing treatment without altering the surface with additional chemical coating. The phase change, surface roughness, change in static and dynamic contact angles due to the heat treatment are studied. Moreover, the surface properties such as frictional force and work of adhesion are calculated for all the samples. The samples annealed at 600 °C shows nearly superhydrophilic with static water contact angle of 12°, frictional force of 85.00748 µN and work of adhesion of 142.3721 mN/m. The surface of TiO2/In2O3 NW is controlled to attain desired water contact angles and sliding angles, which is paramount for designing practical application in self-cleaning, electronic and biomedical fields.