Effects of the surrounding medium on the optical properties of a subwavelength aperture

Influence of the refractive index of the surrounding material on the performance of a C-shaped subwavelength aperture is investigated. The changes in the spectral response (0.6 mu m to 6 mu m wavelength range) and power throughput of the aperture in an optically opaque silver (Ag) film are described for two configurations: one where the film with the aperture is immersed in an infinite dielectric slab and the other where the metallic layer is immediately adjacent to a semi-infinite dielectric substrate. It is shown that, while the resonant wavelengths increase monotonically with refractive index for both cases, the rates of these increases, as well as the behavior of the power throughput, depend not only on the configuration, but also strongly on the transmission mode. These findings have important implications for the design of subwavelength aperture-enhanced devices

Optical transmission properties of C-shaped subwavelength waveguides on silicon

Optical properties of C-shaped subwavelength waveguides in metallic (silver) films on silicon substrates are studied in the range of 0.6-6 mu m. Power throughput and resonant wavelengths of several transmission modes are studied by varying the waveguide length (or metal thickness). Among three types of transmission modes, the fundamental order of the Fabry-Perot-type mode was shown to attain remarkably high power throughputs (as high as 12). With optimized design of the aperture, the resonant wavelength of this mode occurs in the 1-2 mu m wavelength range, suggesting that such apertures can be utilized to achieve plasmonic-enhanced silicon photonic devices at telecommunication wavelengths

Studies of minority carrier diffusion length increase in p-type ZnO : Sb

Minority electron diffusion length was measured in p-type, Sb-doped ZnO as a function of temperature using the electron beam induced current technique. A thermally induced increase of electron diffusion length was determined to have an activation energy of 184 +/- 10 meV. Irradiation with a low energy (5 kV) electron beam also resulted in an increase of diffusion length with a similar activation energy (219 +/- 8 meV). Both phenomena are suggested to involve a Sb-Zn-2V(Zn) acceptor complex. Saturation and relaxation dynamics of minority carrier diffusion length are explored. Details of a possible mechanism for diffusion length increase are presented

ZnO-Based Ultraviolet Photodetectors

Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date

Studies Of Minority Carrier Transport In Zno

The temperature dependence of the minority carrier diffusion length and lifetime in bulk n-type ZnO was studied using Electron-Beam-Induced Current (EBIC) and cathodoluminescence (CL) techniques. The diffusion length was observed to increase exponentially over the temperature range from 25 to 125 {ring operator}C, yielding an activation energy of 45 ± 2 meV. A concomitant decrease of the cathodoluminescence intensity for the near-band-edge transition was also observed. The activation energy determined by optical measurements was 58 ± 7 meV. The larger minority carrier diffusion length and smaller luminescence intensity are attributed to the increased lifetime of non-equilibrium holes in the valence band at elevated temperatures. Carrier trapping on Li-related levels with activation energy 283 ± 9 meV is also addressed. © 2007 Elsevier Ltd. All rights reserved

C-Shaped Subwavelength Apertures For Silicon Photonics Applications

Optical transmission properties of C-shaped apertures in silver films on silicon are studied for subwavelength integrated photonic applications. The fundamental Fabry-Perot-like mode is recognized to attain the highest power throughput at the telecommunication wavelengths. © 2010 Optical Society of America

Subwavelength Plasmonic Apertured Waveguides For Integrated Photonics Applications

Optical transmission properties of subwavelength apertured waveguides on semiconductor substrates, particularly silicon, are studied. The waveguide design is optimized for maximum power throughput at telecommunication wavelengths. © 2010 IEEE

Focused-Ion-Beam Fabrication Of Zno Nanorod-Based Uv Photodetector Using The In-Situ Lift-Out Technique

ZnO nanorods and nanowires are promising candidates as new types of high-sensitivity ultraviolet (UV) photodetectors due to their wide bandgap and large aspect ratio. In this study, single-crystalline ZnO nanorods were grown on glass substrates by a hydrothermal method. Specific structural, morphological, electrical, and optical measurements were carried out. A single ZnO nanorod-based photodetector was fabricated using the in-situ lift-out technique in a focused ion beam (FIB/SEM) instrument and characterized. With a source wavelength of 370 nm and an applied bias of 1 V, the responsivity of the ZnO nanorod is 30 mA/W. The single ZnO nanorod photodetector exhibits an ultraviolet (UV) photoresponse promising for potential applications as cost-effective UV detectors. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA

Propagation Of High-Frequency Surface Plasmons On Gold

Surface plasmon propagation on gold over 0.1-1.6 micrometer distances for plasmon energies in the range 1.6-3.5 eV was characterized. Surface plasmons were excited by an electron beam near a grating milled in the gold. The spectra of out-coupled radiation reveal increasingly strong propagation losses as surface plasmon energy increases above 2.8 eV, but little effect in the range 1.6-2.8 eV. These results are in partial agreement with theoretical expectations. © 2008 Materials Research Society