Photodetectors are widely applied in modern industrial fields because they convert light energy into electrical signals. We propose a printable silver (Ag) paste electrode for a highly flexible metal–semiconductor–metal (MSM) broadband visible light photodetector as a wearable and portable device. Single-crystal and surface-textured silicon substrates with thicknesses of 37.21 μm were fabricated using a wet etching process. Surface texturization on flexible Si substrates enhances the light-trapping effect and minimizes reflectance from the incident light, and the average reflectance is reduced by 16.3% with pyramid-like structures. In this study, semitransparent, conductive Ag paste electrodes were manufactured using a screen-printing with liquid-phase process to form a flexible MSM broadband visible light photodetector. The transmittance of the homemade Ag paste solution fell between 34.83% and 36.98% in the wavelength range of visible light, from 400 nm to 800 nm. The highest visible light photosensitivity was 1.75 × 104 at 19.5 W/m2. The photocurrents of the flexible MSM broadband visible light photodetector were slightly changed under concave and convex conditions, displaying stable and durable bending properties.
We propose a highly preferred c-axis-oriented but random in-plane-oriented nanocrystal to enhance the conversion of thermal to electrical energy for future energy harvesting. A highly preferred c-axis-oriented but random in-plane-oriented ZnO nanocrystal film is successfully fabricated by a homemade precursor flow rate-interrupted atomic layer deposition (ALD) system. Xray diffraction (XRD) results identify only a (002) peak in the ZnO nanocrystal films, and azimuthal ϕ scans reveal no folded symmetry in the films, indicating a highly preferred c-axis-oriented but random in-plane structure. The Seebeck coefficient is −0.345 mV/K, and the power factor is 3.66 × 10 −4 W/(m K 2 ) at 399.65 K as the D-spacing of the (002) orientation expands to 0.421%. These observations suggest that additional electrical conductivity can be induced by the piezoelectric effect in the c-axis lattice plane of the ZnO nanocrystal film and that phonon penetration is blocked by in-plane grain boundaries.
A period-doubling route to chaos was observed in a passively Q-switched Nd:GdVO4 laser beam with azimuthal polarization. At a period of two, the peak intensities gradually varied with the azimuthal angle. When the pump power was increased, the chaotic behavior was spatiotemporal, but the polarization was still azimuthal. To the best of our knowledge, this is the first report of spatiotemporal chaos under a stationary spatial distribution of the polarization.
In this paper, based on Monte Carlo ray tracing we simulate light extraction efficiency and directionality of the light pattern of GaN LEDs implanted with micro-pyramid structure with or without lens encapsulation. We have shown that micro-pyramid structures at some specific slanted angles in the LEDs are useful to increase effective flux utilization through enhancement of both the directionality and light extraction efficiency.
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