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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Effect of DC Electric Field on the Emitted THz Signal of Antenna-Coupled Spintronic Emitters
摘要： We study the impact of an external electric DC field on antenna-coupled spintronic THz emitters driven by a 90 fs, 1550 nm laser oscillator. Simultaneous application of external electric and magnetic field shows a quadratic decrease in peak-peak THz pulse with increase in the bias voltage. We ascribe this decrease to Joule heating caused by the DC current flowing through the spintronic material.
关键词： spintronic emitters,Joule heating,DC electric field,THz
更新于2025-09-12 10:27:22
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Influence of electric field on direct and indirect exciton in a concentrically coupled quantum ring heterostructure embedded in SiO2 matrix
摘要： Excitonic states of Concentric Double Quantum Ring (CDQR) heterostructures embedded in SiO2 matrix under the influence of electric field has been calculated theoretically using variational technique. CDQR has been confined in a quantum well of suitable width which serve as the height of the quantum ring along which the electric field is applied. Central barrier width, outer ring width and carrier location has been tuned to understand the localization of both direct and indirect excitons. Effect of ring dimension and electric field on the energy states of Inner Ring Exciton (IRE) and Outer Ring Exciton (ORE) has been determined. Tilting of conduction and valence bands due to the application of electric field invokes a triangular confinement to the carriers and the same has been discussed. Diamagnetic susceptibility which is merely an indicator of electron hole separation and intersubband transition energy has also been calculated for both symmetric and asymmetric quantum ring. Height of the QR has also been changed to study its effect on the diamagnetic susceptibility of an exciton.
关键词： Diamagnetic Susceptibility,Quantum Ring,Exciton,Binding energy,Electric Field
更新于2025-09-12 10:27:22
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Tailoring the longitudinal electric fields of high-order laser beams and their direct verification in three dimensions
摘要： We demonstrate the tailoring of longitudinal electric fields that arise from tight focusing of spatially phase-shaped high-order laser beams, and verify their spatial distribution in three dimensions. To tailor the three-dimensional (3D) spatial distribution of longitudinal electric fields, we precisely control the relative phase delay between the two lobes of a HG10 laser beam using a spatial light modulator (SLM) before tight focusing. To verify the longitudinal electric fields in the focal volume, we employ 3D microscopic mapping of second-harmonic generation (SHG) from a single semiconductor nanowire that is extremely sensitive to the orientation of the longitudinal electric field. The technique is direct, general and expected to be useful in harnessing and in probing longitudinal electric fields with arbitrary spatial intensity distributions in the 3D focal volume.
关键词： Second-harmonic generation,Polarization,Longitudinal electric field,3D microscopy,Semiconductor nanowire
更新于2025-09-12 10:27:22
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Role of Continuous Spray Pyrolyzed synthesized MoO3 nanorods in PEDOT:PSS matrix by electric field assisted spray deposition for organic photovoltaics
摘要： Organic-inorganic hybrid solution composing of Continuous Spray Pyrolyzed (CoSP) synthesized molybdenum trioxide (MoO3) nanorods in poly(3,4-ethylene dioxy thiophene): poly(styrenesulfonate) (PEDOT:PSS) were developed to form an effective interconnecting layer for use as a hybrid hole transport layer (HTL) in organic solar cells (OSCs). Compared to that of pristine PEDOT:PSS based OSCs, the PEDOT:PSS-MoO3 based OSC demonstrates a noticeable advancement in power conversion efficiency (PCE), current density, and fill factor due to enhanced the wettability and conductivity of the composite HTL for efficient hole injection. The effect of the applied DC voltage (500V and 1000V) to the nozzle during the spray deposition of hybrid PEDOT:PSS-MoO3 HTL on efficient operation of the OSCs was systematically investigated. The surface roughness, compact morphology and hence the electrical conductivity of hybrid HTL are significantly influenced by the applied DC voltages during deposition of film. It is attributed to coulombic fission for better atomization of spray and generating ultrafine homogeneous droplets in corona cone, which fabricate a uniform film over a larger area. Moreover, rise in the work function was also noticed possibly due to the nanostructure formation due to MoO3 nanorods. The use of 500V and 1000V during fabrication of the PEDOT:PSS-MoO3 HTL resulted in the ambient condition optimized PTB7:PC71BM based OSCs reaching highest PCE of 4.68% and 5.11%, respectively. This is due to superior interface connection between hybrid HTL and photoactive layer leading to improved charge collection efficiency.
关键词： hybrid PEDOT:PSS:MoO3 HTL,spray deposition,electric field,organic solar cells
更新于2025-09-12 10:27:22
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Analysis of electroluminescence spectra from high optical-power density forward-biased silicon-led in standard CMOS technology
摘要： A Si-LED with high-power density p+-n junction and wedge-shaped electrodes was fabricated by standard complementary metal oxide-semiconductor (CMOS) process, and its electroluminescence (EL) spectra were measured at different forward currents. By studying the EL spectra, two interesting phenomena were found. One was that the main peak of EL spectra transited from long wavelength (1135 nm) to short wavelength (1078 nm) along with the forward current increased. The other was that two light emission peaks with energy larger than band gap (Eg) were observed. For the first time, reasonable explanations to the two phenomena were given. Here, the peak shift is attributed to that, with forward current increased, the electron-hole pair recombination of the bound excitons without assist of phonons, increases faster than that of those bound or free excitons with assist of phonons. And the existence of two energy-high light emission peaks is resulted from that, under strong electric field, hot holes absorb one or two phonons from the crystal lattice and then recombine with electrons in conduction band.
关键词： Wedge-shaped pinpoint electrode,CMOS standard technology,Electroluminescence (EL) spectra,Silicon-based light-emitting devices (Si-LEDs),Strong electric field
更新于2025-09-12 10:27:22
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Rydberg-State-Resolved Resonant Energy Transfer in Cold Electric-Field-Controlled Intrabeam Collisions of NH <sub/>3</sub> with Rydberg He Atoms
摘要： The resonant transfer of energy from the inversion sublevels in NH3 to He atoms in triplet Rydberg states with principal quantum number n = 38 has been controlled using electric fields below 15 V/cm in intrabeam collisions at translational temperatures of ～1 K. The experiments were performed in pulsed supersonic beams of NH3 seeded in He at a ratio of 1:19. The He atoms were prepared in the metastable 1s2s 3S1 level in a pulsed electric discharge in the trailing part of the beams. The velocity slip between the heavy NH3 and the lighter metastable He was exploited to perform collision studies at center-of-mass collision speeds of ～70 m/s. Resonant energy transfer in the atom?molecule collisions was identified by Rydberg-state-selective electric-field ionization. The experimental data have been compared to a theoretical model of the resonant dipole?dipole interactions between the collision partners based on the impact parameter method.
关键词： NH3,resonant energy transfer,cold collisions,electric-field control,Rydberg states,He
更新于2025-09-12 10:27:22
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Exciton-phonon properties in cylindrical quantum dot with parabolic confinement potential under electric field
摘要： The mixed confinement potential effect on exciton in cylindrical quantum dot (QD) is calculated in the presence of an electric field with and without confined longitudinal optical (LO) phonon mode contribution. The variational approach within the effective mass approximation is used to describe the exciton-phonon interaction with three variational parameters of the trial wave function. The ground state binding energy of exciton has been calculated numerically for the parabolic (axial direction) and square (lateral direction) finite confinement potentials under the electric field applied along the growth direction of the QD. The system both with and without LO-phonon contribution is investigated. The combined effects of applied electric field and parabolic confinement on the ground state binding energy, the polaronic correction and the Stark shift are examined in detail. The findings indicate that the electric field strongly reduces the binding energy in both ignoring and considering LO-phonon interaction especially for wider thickness of QD. We have shown that the contribution of LO-phonon leads to an increase in the binding energy and to decrease in the Stark shift energy. Furthermore, our numerical results illustrate a strong dependence of Stark shift on the QD height, electric field strength and LO-phonon contribution.
关键词： Parabolic potential,Electric field,Binding energy,Exciton-LO-phonon,Stark shift
更新于2025-09-12 10:27:22
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External electric field effect on exciton binding energy in GaAs /GaAlAs cylindrical quantum dots with asymmetric axial potential
摘要： The present study investigates theoretically the role of applied electric field on the exciton binding energy and photoluminescence energy in cylindrical quantum dot (QD) by considering an asymmetric axial potential. As a framework, we have considered the variational approach and the correlation between the electron and hole in the trial wave function within the effective-mass approximation. We have calculated the exciton binding energy of the ground state and the photoluminescence energy as the function of the geometry and the strength of the applied electric field along the growth direction of the cylinder. Our numerical findings for GaAs/Ga(1-x)Al(x)As have shown that the binding energy is decreasing function of the electric field strength. Also, we have found that the exciton binding energy is decreasing function of the QD height with and without electric field effect. Furthermore, the photoluminescence energy depends on the effects of electric field, the geometrical confinement and the aluminum concentrations in the barrier materials.
关键词： Exciton,Photoluminescence,Electric field,Asymmetric Quantum Dots
更新于2025-09-12 10:27:22
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Interband optical absorption in wurtzite GaN/InxGa1?xN/GaN spherical quantum dots with built-in electric field
摘要： Based on the principle of density matrix and the finite element method, the interband optical absorption between the electron and hole has been investigated in a wurtzite GaN/InxGa1?xN/GaN spherical core–shell quantum dot (CSQD) including a strong built-in electric field (BEF). We have studied the effects of the size and the ternary mixed crystal on the optical absorption coefficients (ACs) and refraction index changes (RICs). The results indicate that the absorption peaks of ACs and RICs decrease rapidly, and show a redshift with the increase of the component x. It is also found that the absorption peaks of ACs and RICs reduce obviously and depend on the core radius and the well width. When the core radius increases, the positions of the maximum ACs and RICs show a blueshift. At the same time, it presents a redshift when the well width increases. Particularly, the influence of the well width is much stronger than the core radius in the wurtzite GaN/InxGa1?xN/GaN spherical CSQDs. We hope that these results could provide guidance on both theoretical and experimental study related to the optical properties of spherical CSQDs.
关键词： Core–shell quantum dot,built-in electric field,optical property,ternary mixed crystal effect
更新于2025-09-12 10:27:22
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A theoretical insight into multiple charge-transfer mechanisms at the P3HT/non-fullerenes interface in organic solar cells
摘要： Poly(3-hexylthiophene) (P3HT)-based organic solar cells (OSCs) have been developed in recent years because of easy-production, low-cost and large-area manufacture. However, fewer non-fullerene acceptors with higher power conversion efficiency (PCE) than PC61BM have been explored in P3HT-based OSCs. In this contribution, the excited states were in-depth analyzed towards probing the particularities of superior P3HT/non-fullerene systems. Multiple charge-transfer (CT) mechanisms involving intermolecular electric field (IEF), hot CT states and direct excitation of CT states were found, which suggests more favorable CT pathways exist in these P3HT/non-fullerene interfaces. Accordingly, the calculations on charge-transfer rates of all the investigated donor/acceptor interfaces further verified the positive effect of multiple CT pathways. In addition, the interesting hybrid Frenkel-CT states were firstly found to be relevant with the stronger electrostatic surface potential (ESP) differences on donor and acceptor for these P3HT/non-fullerene systems, which may provide a strategy for the design of high-efficiency OSCs.
关键词： non-fullerene,intermolecular electric field (IEF),P3HT,hybrid Frenkel-CT states,charge-transfer (CT) mechanisms,Organic solar cells (OSCs)
更新于2025-09-12 10:27:22