The Ag-doped ZnO films were deposited on Si substrates by dc reactive sputtering. Obvious enhancement of ultraviolet (UV) emission of the samples was observed due to Ag2O nanoclusters formatted during Ag doping. The UV emission consisted of two peaks. The 348nm peak was attributed to Ag2O nanoclusters, and the 382nm one was attributed to ZnO. The strongest UV emission of a certain ZnO–Ag2O film was over ten times stronger than that of a pure ZnO film, which was an exciting result. The enhancement of UV emission was caused by excitons formed at the interface between Ag2O nanoclusters and ZnO grains.

Interstitial carbides are able to maintain structural stability even with a high concentration of carbon vacancies. This feature provides them with tunable properties through the design of carbon vacancies, and thus making it important to reveal how carbon vacancies affect their properties. In the present study, using first-principles, we have calculated the properties of a number of stable and metastable zirconium carbides ZrC1-x (x = 0 and 1/n, n = 2-8) which were predicted by the evolutionary algorithm USPEX. Effects of carbon vacancies on the structures, mechanical properties, and chemical bonding of these zirconium carbides were systematically investigated. The distribution of carbon vacancies has significant influence on mechanical properties, especially Pugh's ratio. Nonadjacent carbon vacancies enhance Pugh's ratio, while grouped carbon vacancies decrease Pugh's ratio. This is explained by the changes in strength of Zr-C and Zr-Zr bonding around differently distributed carbon vacancies. We further explored the mechanical properties of zirconium carbides with impurities (N and O) by inserting N and O atoms into the sites of carbon vacancies. The enhanced mechanical properties of zirconium carbides were found.

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A Schottky UV photodetector based on graphene/ZnO:Al nanorod-array-film (AZNF) structure has been fabricated. Different from the previously reported graphene/ZnO photodetectors, this photodetector has a stable Schottky barrier which does not disappear under UV light. Thus, the UV photodetector can work as a high-performance self-powered device. The key to improve the stability of the Schottky barrier is a two-step surface treatment process. As a result, the self-powered photodetector exhibits a UV-to-visible rejection ratio of about 1 × 10, a responsivity of 0.039 A W, a short rise time of 37 μs, and a decay time of 330 μs. Furthermore, the photodetector is able to keep the responsivity under low light conditions. In comparison with the previously reported graphene/ZnO UV photodetectors, the photodetector exhibits a higher responsivity at zero bias and a faster response speed. This study provides a potential way to fabricate high-performance self-powered UV photodetectors.

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An Sb/InSe heterostructure manifests a varied direct bandgap under an electric field which is more favorable to FETs and MEMS devices.

Chromium hydride is a prototype stoichiometric transition metal hydride. The phase diagram of Cr-H system at high pressures remains largely unexplored due to the challenges in dealing with the high activation barriers and complications in handing hydrogen under pressure. We have performed an extensive structural study on Cr-H system at pressure range 0 ∼ 300 GPa using an unbiased structure prediction method based on evolutionary algorithm. Upon compression, a number of hydrides are predicted to become stable in the excess hydrogen environment and these have compositions of Cr2Hn (n = 2–4, 6, 8, 16). Cr2H3, CrH2 and Cr2H5 structures are versions of the perfect anti-NiAs-type CrH with ordered tetrahedral interstitial sites filled by H atoms. CrH3 and CrH4 exhibit host-guest structural characteristics. In CrH8, H2 units are also identified. Our study unravels that CrH is a superconductor at atmospheric pressure with an estimated transition temperature (T c) of 10.6 K, and superconductivity in CrH3 is enhanced by the metallic hydrogen sublattice with T c of 37.1 K at 81 GPa, very similar to the extensively studied MgB2.

In this paper, the structural, electronic, and magnetic properties as well as the relative stabilities of fully and partially hydrogenated AlN nanosheets have been systematically investigated by first-principles calculations based on density functional theory. The results indicate that full hydrogenation is more energetically favorable for thinner AlN nanosheets, whereas semi-hydrogenation at N sites is preferred for thicker ones. Moreover, semiconductor → half-metal → metal transition with nonmagnetic → magnetic transfer can be achieved for AlN nanosheets by surface hydrogenation and increasing nanosheet thickness. The diverse electronic and magnetic properties highlight the potential applications of AlN nanosheets in electronics and spintronics.