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The CuO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method and modified with CdS quantum dots by successive ionic layer adsorption and reaction (SILAR). CdS QDs modified CuO IOPCs FTO electrodes of different SILAR cycles were fabricated and their electrochemical properties were studied by cyclic voltammetry (CV) and chronoamperometry (I–t). Structure and morphology of the samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution TEM (HRTEM), Energy-dispersive X-ray analysis (EDX) and X-ray diffraction pattern (XRD). The result indicated that the structure of IOPCs and loading of CdS QDs could greatly improve the electrochemical properties. Three SILAR cycles of CdS QDs sensitization was the optimum condition for preparing electrodes, it exhibited a sensitivity of 4345 μA mM-1 cm-2 to glucose with a 0.15 μM detection limit (S/N= 3) and a linear range from 0.15 μM to 0.5 mM under a working potential of +0.7 V. It also showed strong stability, good reproducibility, excellent selectivity and fast amperometric response. This work provides a promising approach for realizing excellent photoelectrochemical nonenzymatic glucose biosensor of similar composite structure.

In this paper, we demonstrate high-performance quasi-vertical GaN-on-Sapphire Schottky barrier diodes (SBD) with a reverse GaN p-n junction termination (RPN). The SBD has a current output of 1 kA/cm 2 at V F = 2.5 V, a low V on of 0.66 V ± 0.017 V, a low R on,sp of 1.4 m •cm 2 , current ON/OFF ratio of over 10 9 (−3 V∼3 V). By introducing the RPN, the breakdown voltage can boost from 459 V to 1419 V, and power figure-of-merit (FOM) can reach 1438 MV/cm 2. It is shown that the presence of the RPN with a suitable anode recess depth can generate an electric field (EF) opposite to the built-in EF at the center of the second top p-n junction, which can decrease the EF peak intensity and make the electric field more uniformly distributed inside the device. Finally, the leakage current of the SBD is inhibited and the breakdown voltage is increased. INDEX TERMS Vertical GaN-on-Sapphire Schottky barrier diode, reverse p-n GaN junction, breakdown voltage, power FOM.

In this work, a new photoelectrochemical biosensor based on Ag2S nanoparticles (NPs) modified macroporous ZnO inverse opals structure (IOs) was developed for sensitive and rapid detection of alpha fetal protein (AFP). Small size and uniformly dispersed Ag2S NPs were prepared using the Successive Ionic Layer Adsorption And Reaction (SILAR) method, which were adsorbed on ZnO IOs surface and frame work as matrix for immobilization of AFP. The composite structure of ZnO/Ag2S expanded the scope of light absorption to long wavelength, which can make full use of the light energy. Meanwhile, an effective matching of energy levels between the conduction bands of Ag2S and ZnO are beneficial to the photo-generated electrons transfer. The biosensors based on FTO (fluorine-doped tinoxide) ZnO/Ag2S electrode showed enough sensitivity and a wide linear range from 0.05 ng/mL to 200 ng/mL with a low detection limit of 8 pg/mL for the detection of AFP. It also exhibited high reproducibility, specificity and stability. The proposed method was potentially attractive for achieving excellent photoelectrochemical biosensor for detection of other proteins.

Ultraviolet (UV) photodetectors have been fabricated on a graphene/4H-SiC wafer. In this device, the electrical doping in the graphene layer, under the gate, is realized by changing the gate voltage while the optical doping in the graphene layer outside the gate region is realized through the photogenerated carrier injection from SiC, by laser excitation at 325 nm. This kind of dual modulation of optical and electric fields ultimately results in the formation of a planar n-p-n or n-n-n junction in the graphene layer. The photoresponse results demonstrate that the planar n-p-n junction is formed at the negative gate voltage, and facilitates negative photoconductivity. The n-n-n junction is formed at the positive gate voltage and facilitates normal photoconductivity. The maximum responsivity, which is attributable to the high photoconductive gain in the planar n-n-n junction, is 254.1A W −1 , at drain-source voltage of −3 V and gate-source voltage of 3 V. Based on these results, the estimated lifetime of the electrons in the graphene channel extends greatly to more than four orders of magnitude longer than that in the isolated graphene. The above results prove that this graphene/4H-SiC combined structure possesses great potential in practical UV-detection applications.

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