Search results for "Toe"

Time-resolved pulsed OSL of ceramic YAP:Mn phosphors

2019

The paper deals with the results of comparative study on time-resolved pulsed optically stimulated luminescence (TR-OSL) response of ceramic YAP:Mn materials prepared by different methods. In parti...

Study of the P3HT/PCBM interface using photoemission yield spectroscopy

2016

Photogeneration efficiency and charge carrier extraction from active layer are the parameters that determine the efficiency of organic photovoltaics (OPVs). Devices made of organic materials often consist of thin (up to 100nm) layers. At this thickness different interface effects become more pronounced. The electron affinity and ionization energy shift can affect the charge carrier transport across metal-organic interface which can affect the performance of the entire device. In the case of multilayer OPVs, energy level compatibility at the organic-organic interface is as important. Photoemission yield spectroscopy was used for organic-organic interface study by ionization energy measuremen…

Outstanding nonlinear optical properties of methylammonium- and Cs-PbX3 (X = Br, I, and Br–I) perovskites: Polycrystalline thin films and nanoparticl…

2019

Metal Halide Perovskites (MHPs) have arisen as promising materials to construct cost-effective photovoltaic and light emission devices. The study of nonlinear optical properties of MHPs is necessary to get similar success in nonlinear photonic devices, which is practically absent in the literature. The determination of the third order nonlinear coefficients is typically done by the Z-scan technique, which is limited by the scattering of polycrystalline thin films. In this work, we have studied nonlinear optical properties of polycrystalline CH3NH3PbX3 (MAPbX3) thin films and colloidal CsPbX3 nanoparticles with three different bandgaps (X3 = I3, Br3, and Br1.5I1.5). Their bright generation o…

Assembly of microparticles by optical trapping with a photonic crystal nanocavity

2012

International audience; In this work, we report the auto-assembly experiments of micrometer sized particles by optical trapping in the evanescent field of a photonic crystal nanocavity. The nanocavity is inserted inside an optofluidic cell designed to enable the real time control of the nanoresonator transmittance as well as the real time visualization of the particles motion in the vicinity of the nanocavity. It is demonstrated that the optical trap above the cavity enables the assembly of multiple particles in respect of different stable conformations.

2019

We systematically study the pump-wavelength dependence of terahertz pulse generation in thin-film spintronic THz emitters composed of a ferromagnetic CoFeB layer between adjacent nonmagnetic W and Pt layers. We find that the efficiency of THz generation is essentially flat for excitation by 150 fs pulses with center wavelengths ranging from 900 to 1500 nm, demonstrating that the spin current does not depend strongly on the pump photon energy. We show that the inclusion of dielectric overlayers of TiO2 and SiO2, designed for a particular excitation wavelength, can enhance the terahertz emission by a factor of up to two in field.

Fabrication and characterization of low cost Cu 2 O/ZnO:Al solar cells for sustainable photovoltaics with earth abundant materials

2016

Abstract The low cost electrodeposition method was used to grow Cu2O thin films and experimentally determine the optimal absorber layer thickness. Raman scattering studies indicate the presence of solely crystalline Cu2O and SEM images show that the thin films consist of grains with a pyramidal shape. The influence of the thickness of the light absorbing Cu2O layer on the basic characteristic of the heterojunction and their properties have been investigated using reflectivity, current–voltage (J–V), capacitance–voltage (C–V) and the external quantum efficiency (EQE) measurements. The depletion layer, the charge collection length of the minority carrier, and reflectivity are the main factors…

Temperature Dependent Suns-V<inf>oc</inf> of Multicrystalline Silicon Solar Cells from Different Ingot Positions

2018

This paper presents temperature dependent Suns- Voc measurements on multicrystalline silicon cells originating from different ingot positions. The effective lifetime is found to increase for all cells when the temperature is increased from 25°C to 6°C. However, cells from the top of the ingot show a considerably larger increas 40–50% for illumination conditions of 0.1-1 Sun, compared to an increase of 20-30% observed for cells from the bottom. The decrease in Voc with increasing temperature is found to be lower for cells from the top of the ingot compared to cells from the bottom. The temperature coefficient of the Voc is found to vary 5% along the ingot at 1 Sun, highlighting the influence…

SiC MOSFET vs SiC/Si Cascode short circuit robustness benchmark

2019

Abstract Nowadays, MOSFET SiC semiconductors short circuit capability is a key issue. SiC/Si Cascodes are compound semiconductors that, in some aspects, show a similar MOSFET behaviour. No interlayer dielectric insulation suggests, in theory, Cascode JFETs as more robust devices. The purpose of this paper is to compare the drift and degradation of two commercial devices static parameters by exposing them to different levels of repetitive 1.5 μs short-circuit campaigns at 85% of its breakdown voltage. Short-circuit time has been set experimentally, and longer times result in catastrophic failure of MOSFET devices due to over self-heating. For this purpose, pre- and post-test short circuit ch…

Selective Band Gap to Suppress the Spurious Acoustic Mode in Film Bulk Acoustic Resonator Structures

2018

In this work, we investigate numerically the propagation of Lamb waves in a film bulk acoustic resonator (FBAR) structure formed by piezoelectric ZnO layer sandwiched between two Mo electrodes coupled with Bragg reflectors; the system is thus considered as a phononic-crystal (PnC) plate. The aim is to suppress the first-order symmetric Lamb wave mode considered as a spurious mode caused by the establishment of a lateral standing wave due to the reflection at the embedded lateral extremities of the structure; this spurious mode is superposing to the main longitudinal mode resonance of the FBAR. The finite element study, using harmonic and eigen-frequency analyses, is performed on the section…

2018

Damping distances of surface plasmon polariton modes sustained by different thin titanium nitride (TiN) films are measured at the telecom wavelength of 1.55 μm. The damping distances are correlated to the electrical direct current resistivity of the films sustaining the surface plasmon modes. It is found that TiN/Air surface plasmon mode damping distances drop non-linearly from 40 to 16μm as the resistivity of the layers increases from 28 to 130μΩ.cm, respectively. The relevance of the direct current (dc) electrical resistivity for the characterization of TiN plasmonic properties is investigated in the framework of the Drude model, on the basis of parameters extracted from spectroscopic ell…