Photoelectric characteristics of hydrogen-terminated polycrystalline diamond MESFETs.

In the field of diamond MESFETs, this work is what we believe to be the first to investigate the optoelectronic properties of hydrogen-terminated polycrystalline diamond MESFETs under visible and near-UV light irradiation. It is shown that the diamond MESFETs are well suited for weak light detection in the near-ultraviolet region around the wavelength of 368 nm, with a responsivity of 6.14 × 106 A/W and an external quantum efficiency of 2.1 × 107 when the incident light power at 368.7 nm is only 0.75 µW/cm2. For incident light at 275.1 nm, the device's sensitivity and EQE increase as the incident light power increases; at an incident light power of 175.32 µW/cm2 and a VGS of -1 V, the device's sensitivity is 2.9 × 105 A/W and the EQE is 1.3 × 106. For incident light in the wavelength range of 660 nm to 404 nm with an optical power of 70 µW/cm2, the device achieves an average responsivity of 1.21 × 105 A/W. This indicates that hydrogen-terminated polycrystalline diamond MESFETs are suitable for visible and near-UV light detection, especially for weak near-UV light detection. However, the transient response test of the device shows a long relaxation time of about 0.2 s, so it is not yet suitable for high-speed UV communication or detection.

Nitrogen Ion Implantation-Modified Cu Substrate for Stable Lithium Metal Anode.

As the only commercialized negative current collector, copper (Cu) foil possesses insurmountable applicational advantages as a lithium metal anode (LMA) substrate. However, the successful usage of Cu foil is limited by the poor Li affinity and crystal face variation, which will lead to severe lithium dendrite growth and poor cyclability. Herein, an industrial-popular ion implantation technique is first adopted for Cu surface modification. With the high-energy implantations of N+ plasma, the unique N-rich transition interface can be formed, among which the lithiophilic CuxNy with extended crystal domains can have uniform Cu crystal faces and offer benefit for Li nucleation/deposition; besides, the induced Li3N-rich SEI with high ionic conductivity can support Li-ion transport kinetics, suppress Li dendrite growth, and mitigate the side reaction to improve LMA stability. Consequently, a uniform Li nucleation/deposition is achieved, with obviously enhanced cycling stability and rate capability for the full cells. This technological maturity ion implantation method can be readily extended to any non/metallic ion species, or joint implantation of bi/multiple ions, and other substrates, demonstrating a possible route to surmount the metal anode challenges.

Large-area aligned branched Cu(2)S nanostructure arrays: room-temperature synthesis and growth mechanism.

In this work, an effective approach to synthesize large-area Cu(2)S hierarchical nanotree arrays is presented: Cu nanowire arrays synthesized via template-assisted electrodeposition are used as precursors for the self-growth of branched Cu(2)S nanotree arrays by a gas-solid reaction in H(2)S atmosphere at room temperature. The branched Cu(2)S nanotrees with a high aspect ratio are vertically aligned over the Au film surface, forming a nanoscale 'forest'. Electron microscopy studies reveal that the treelike branched nanostructures are composed of an end-capped tubular Cu(2)S trunk and radially organized Cu(2)S nanorod branches over the trunk. A formation mechanism of the hollow trunk and the nanobranches is proposed on the basis of experimental observations.