Novel BN hollow nanoribbons (BNHNRs) were fabricated by a simple ZnS nanoribbon templating method. Such BNHNRs have a distinct structure and show unique optical properties, as demonstrated from Raman, Fourier transform infrared spectroscopy, UV-vis spectroscopy, and cathodoluminescence spectroscopy, when compared with other forms of BN nanostructures. With high crystallinity, the BNHNRs exhibit an extraordinary ultraviolet CL emission at 5.33 eV. Such a property is highly advantageous for optoelectronic applications, particularly in the ultraviolet region, such as blue lasing and light emitting diodes. This templating method has also been extended to synthesize other hollow nanostructures such as boron carbonitride. This study represents a new methodology for fabricating hollow nanostructures with defined crystallinity and unique optical properties.

Studies on atomic layer deposition Al2O3/In0.53Ga0.47As interface formation mechanism based on air-gap capacitance-voltage method Appl. Phys. Lett. 101, 122102 (2012) A mathematical model for void evolution in silicon by helium implantation and subsequent annealing process J. Appl. Phys. 112, 064302 (2012) Void evolution in silicon under inert and dry oxidizing ambient annealing and the role of a Si1−xGex epilayer cap Defects in hydrothermal grown ZnO single crystals are studied as a function of annealing temperature using positron annihilation, x-ray diffraction, Rutherford backscattering, Hall, and cathodoluminescence measurements. Positron lifetime measurements reveal the existence of Zn vacancy related defects in the as-grown state. The positron lifetime decreases upon annealing above 600°C, which implies the disappearance of Zn vacancy related defects, and then remains constant up to 900°C. The Rutherford backscattering and x-ray rocking curve measurements show the improvement of crystal quality due to annealing above 600°C. Although the crystal quality monitored by x-ray diffraction measurements is further improved after annealing at above 1000°C, the positron lifetime starts to increase. This is due to either the formation of Zn vacancy related defects, or the change of the Zn vacancy charge state occupancy as a result of the Fermi level movement. The electron concentration increases continuously with increasing annealing temperature up to 1200°C, indicating the formation of excess donors, such as oxygen vacancies or zinc interstitials. The cathodoluminescence measurements reveal that the ultraviolet emission is greatly enhanced in the same temperature range. The experimental results show that the ZnO crystal quality, electrical and optical characteristics are improved by postgrowth annealing from 600 to 1200°C. The disappearance of Zn vacancy related defects contributes to the initial stage of improved crystal quality.

Background Coronavirus disease (COVID-19) has become a pandemic. The knowledge, attitudes, and practices (KAP) of the public play a major role in the prevention and control of infectious diseases. The objective of the present study was to evaluate the KAP of the Chinese public and to assess potential influencing factors related to practices. Methods A cross-sectional online survey was conducted in China in February 2020 via a self-designed questionnaire comprising 33 questions assessing KAP. Results For the 2136 respondents from 30 provinces or municipalities in China, the accurate response rate for the knowledge section ranged from 72.7 to 99.5%, and the average was 91.2%. Regarding attitude section, the percentage of positive attitudes (“strongly agree” and “agree”) ranged from 94.7 to 99.7%, and the average value was 98.0%. The good practices (“always” and “often”) results ranged from 76.1 to 99.5%, and the average value was 96.8%. The independent samples t-test revealed that gender and ethnic differences had no effect on knowledge, attitude or behaviour (P > 0.05). However, knowledge was associated with age (t = 4.842, p < 0.001), marital status (t = − 5.323, p < 0.001), education level (t = 8.441, p < 0.001), occupation (t = − 10.858, p < 0.001), and place of residence (t = 7.929, p < 0.001). Similarly, attitude was associated with marital status (t = − 2.383, p = 0.017), education level (t = 2.106, p = 0.035), occupation (t = − 4.834, p < 0.001), and place of residence (t = 4.242, p < 0.001). The multiple linear regression analysis results showed that the factors influencing practices were knowledge (t = − 3.281, p = 0.001), attitude (t = 18.756, p < 0.001), occupation (t = − 3.860, p < 0.001), education level (t = 3.136, p = 0.002), and place of residence (t = 3.257, p = 0.001). Conclusions The Chinese public exhibited a good level of knowledge of COVID-19, a positive attitude, and high adherence to good practices. COVID-19-related knowledge, attitudes and practices were affected by age, marital status, education level, occupation, and place of residence to varying degrees. In addition, practices were affected by knowledge and attitudes towards COVID-19.

High‐quality, uniform one‐dimensional CdS micro/nanostructures with different morphologies—microrods, sub‐microwires and nanotips—are fabricated through an easy and effective thermal evaporation process. Their structural, cathodoluminescence and field‐emission properties are systematically investigated. Microrods and nanotips exhibit sharp near‐band‐edge emission and broad deep‐level emission, whereas sub‐microwires show only the deep‐level emission. A significant decrease in a deep‐level/near‐band‐edge intensity ratio is observed along a tapered nanotip towards a smaller diameter part. This behavior is understood by consideration of defect concentrations in the nanotips, as analyzed with high‐resolution transmission electron microscopy. Field‐emission measurements show that the nanotips possess the best field‐emission characteristics among all 1D CdS nanostructures reported to date, with a relatively low turn‐on field of 5.28 V µm−1 and the highest field‐enhancement factor of 4 819. The field‐enhancement factor, turn‐on and threshold fields are discussed related to structure morphology and vacuum gap variations under emission.

Articles you may be interested inReuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Phosphorus ions were implanted in ZnO single crystals with energies of 50-380 keV having total doses of 4.2ϫ 10 13 -4.2ϫ 10 15 cm −2 . Positron annihilation measurements reveal the introduction of vacancy clusters after implantation. These vacancy clusters grow to a larger size after annealing at a temperature of 600°C. Upon further annealing up to a temperature of 1100°C, the vacancy clusters gradually disappear. Raman-scattering measurements reveal the enhancement of the phonon mode at approximately 575 cm −1 after P + implantation, which is induced by the production of oxygen vacancies ͑V O ͒. These oxygen vacancies are annealed out up to a temperature of 700°C accompanying the agglomeration of vacancy clusters. The light emissions of ZnO are suppressed after implantation. This is due to the competing nonradiative recombination centers introduced by implantation. The recovery of the light emission occurs at temperatures above 600°C. The vacancy-type defects detected by positrons might be part of the nonradiative recombination centers. The Hall measurement indicates an n-type conductivity for the P + -implanted ZnO layer, suggesting that phosphorus is an amphoteric dopant.