Linearly polarized and time-resolved cathodoluminescence study of strain-induced laterally ordered (InP)2/(GaP)2 quantum wires

1997 ◽  
Vol 81 (10) ◽  
pp. 6837-6852 ◽  
Author(s):  
D. H. Rich ◽  
Y. Tang ◽  
H. T. Lin
Keyword(s):  
Quantum Wires ◽  
Time Resolved ◽  
Linearly Polarized ◽  
Cathodoluminescence Study

Polarized Cathodoluminescence Study of (InP)2/(GaP)2 Bilayer Superlattice Structures

1995 ◽  
Vol 379 ◽  
Author(s):  
Y. Tang ◽  
K. Rammohan ◽  
H.T. Lin ◽  
D.H. Rich ◽  
P. Colter ◽  
...  
Keyword(s):  
Quantum Wires ◽  
Spectral Lineshape ◽  
Superlattice Structure ◽  
Electron Beam Excitation ◽  
Optical Effects ◽  
Nonlinear Optical Effects ◽  
Linearly Polarized ◽  
Imaging And Spectroscopy ◽  
Superlattice Structures ◽  
Cathodoluminescence Study

ABSTRACTLinearly polarized cathodoluminescence (LPCL) imaging and spectroscopy techniques have been employed to examine the optical properties and homogeneity of (InP)2/(GaP)2 bilayer superlattice (BSL) structures which exhibit a lateral composition modulation that leads to the formation of quantum wires. LPCL spectra were measured for various temperature and electron beam excitation densities. The magnitude of the polarization anisotropy and spectral lineshape are found to depend sensitively on the excitation conditions, revealing large nonlinear optical effects in these samples. CL images reveal that defects in the bilayer superlattice structure originate from the GaAs substrate or the initial stages of InGaP growth.

An instrument for time-resolved and anomalous simultaneous small- and wide-angle X-ray scattering (SWAXS) at NSRRC

2006 ◽  
Vol 39 (6) ◽  
pp. 871-877 ◽  
Author(s):  
Ying-Huang Lai ◽  
Ya-Sen Sun ◽  
U-Ser Jeng ◽  
Jhih-Min Lin ◽  
Tsang-Lang Lin ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Quantum Wires ◽  
Grazing Incidence ◽  
Anomalous Scattering ◽  
Wide Angle ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

A SWAXS (small- and wide-angle X-ray scattering) instrument was recently installed at the wiggler beamline BL17B3 of the National Synchrotron Radiation Research Center (NSRRC), Taiwan. The instrument, which is designed for studies of static and dynamic nanostructures and correlations between the nano (ormeso) structure (SAXS) and crystalline structure (WAXS), provides a flux of 1010–1011photon s−1at the sample at energies between 5 and 14 keV. With a SAXS area detector and a WAXS linear detector connected to two data acquisition systems operated in master–slave mode, the instrument allows one to perform time-resolved as well as anomalous scattering measurements. Data reduction algorithms have been developed for rapid processing of the large SWAXS data sets collected during time-resolved measurements. The performance of the instrument is illustrated by examples taken from different classes of ongoing projects: (i) time-resolved SAXS/WAXS/differential scanning calorimetry (DSC) with a time resolution of 10 s on a semicrystalline poly(hexamethylene terephthalate) sample, (ii) anomalous SAXS/WAXS measurements on a nanoparticulate PtRu catalyst, and (iii) grazing-incidence SAXS of a monolayer of oriented semiconductor quantum wires, and humidity-controlled ordering of Alamethicin peptides embedded in an oriented lipid membrane.

scholarly journals Ultrafast isomerization-induced cooperative motions to higher molecular orientation in smectic liquid-crystalline azobenzene molecules

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Masaki Hada ◽  
Daisuke Yamaguchi ◽  
Tadahiko Ishikawa ◽  
Takayoshi Sawa ◽  
Kenji Tsuruta ◽  
...  
Keyword(s):  
Molecular Orientation ◽  
Soft Matter ◽  
Liquid Crystalline ◽  
Laser Polarization ◽  
Time Resolved ◽  
Cooperative Motion ◽  
Subsequent Response ◽  
Molecular Dynamics Calculations ◽  
Polarization Axis ◽  
Linearly Polarized

Abstract The photoisomerization of molecules is widely used to control the structure of soft matter in both natural and synthetic systems. However, the structural dynamics of the molecules during isomerization and their subsequent response are difficult to elucidate due to their complex and ultrafast nature. Herein, we describe the ultrafast formation of higher-orientation of liquid-crystalline (LC) azobenzene molecules via linearly polarized ultraviolet light (UV) using ultrafast time-resolved electron diffraction. The ultrafast orientation is caused by the trans-to-cis isomerization of the azobenzene molecules. Our observations are consistent with simplified molecular dynamics calculations that revealed that the molecules are aligned with the laser polarization axis by their cooperative motion after photoisomerization. This insight advances the fundamental chemistry of photoresponsive molecules in soft matter as well as their ultrafast photomechanical applications.

scholarly journals Ultrafast Modulation of Magnetization Dynamics in Ferromagnetic (Ga, Mn)As Thin Films

2018 ◽  
Vol 8 (10) ◽  
pp. 1880 ◽  
Author(s):  
Hang Li ◽  
Xinhui Zhang ◽  
Xinyu Liu ◽  
Margaret Dobrowolska ◽  
Jacek Furdyna
Keyword(s):  
Magnetic Anisotropy ◽  
Spin Dynamics ◽  
Optical Excitation ◽  
Laser Pulses ◽  
Time Resolved ◽  
Ultrafast Optical ◽  
Optical Effects ◽  
Out Of Plane ◽  
Linearly Polarized ◽  
Magnetization Precession

Magnetization precession induced by linearly polarized optical excitation in ferromagnetic (Ga,Mn)As was studied by time-resolved magneto-optical Kerr effect measurements. The superposition of thermal and non-thermal effects arising from the laser pulses complicates the analysis of magnetization precession in terms of magnetic anisotropy fields. To obtain insight into these processes, we investigated compressively-strained thin (Ga,Mn)As films using ultrafast optical excitation above the band gap as a function of pulse intensity. Data analyses with the gyromagnetic calculation based on Landau-Lifshitz-Gilbert equation combined with two different magneto-optical effects shows the non-equivalent effects of in-plane and out-of-plane magnetic anisotropy fields on both the amplitude and the frequency of magnetization precession, thus providing a handle for separating the effects of non-thermal and thermal processes in this context. Our results show that the effect of photo-generated carriers on magnetic anisotropy constitutes a particularly effective mechanism for controlling both the frequency and amplitude of magnetization precession, thus suggesting the possibility of non-thermal manipulation of spin dynamics through pulsed laser excitations.

Structure and Photoluminescence Investigations of Self-Organized InAs/GaAs Quantum Wires

2009 ◽  
Vol 79-82 ◽  
pp. 1707-1710
Author(s):  
Ling Min Kong ◽  
Cun Xi Zhang ◽  
Rui Wang ◽  
Shi Lai Wang
Keyword(s):  
Quantum Wires ◽  
Energy Levels ◽  
Dynamical Behavior ◽  
Time Resolved ◽  
Force Microscopy ◽  
Long Wavelength ◽  
Self Organized ◽  
Atomic Force ◽  
Two Samples ◽  
Localized Excitons

Self –organized InAs quantum wires (QWRs) were fabricated on the step edges of GaAs (331)A surface by molecular beam epitaxy (MBE). The atomic force microscopy (AFM) results show that the lateral size of InAs QWRs is 90 nm while the size along the step lines increasing with the thicknesses of InAs layers, amounting to 1100nm. The height of InAs QWRs varies from 7.9nm to 13nm. Photoluminescence (PL) measurements on the two samples were explored and an obvious PL peak around 967 nm was observed at 25 K. The PL intensity decreases as the temperature increases, and it will vanish above 60 K. However, the QWR sample with thicker InAs layer emits a long emission of 1100 nm -1400 nm as the temperature rises above 50 K, and a longer emission of 1400-1600nm as the temperature approaches to 100 K. We considered that the complex photoluminescence spectra were originated from the multiple energy steps. The carrier migration among the different QWRs structures intensified with temperature, and the chance rate from the higher energy levels to the lower ones which generated a stronger emission of long wavelength. The carrier dynamics of QWR samples were measured by using time resolved PL (TRPL) spectra from 25 K to 100 K. The PL decay time in the QWR structure at longer emission was found to be independent of the temperature as T<100 K, showing a typical dynamical behavior of the localized excitons.

scholarly journals Low-temperature time-resolved cathodoluminescence study of exciton dynamics involving basal stacking faults in a-plane GaN

2009 ◽  
Vol 94 (20) ◽  
pp. 201115 ◽  
Author(s):  
P. Corfdir ◽  
J. Ristić ◽  
P. Lefebvre ◽  
T. Zhu ◽  
D. Martin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Stacking Faults ◽  
Time Resolved ◽  
Exciton Dynamics ◽  
Temperature Time ◽  
Cathodoluminescence Study

Temperature dependent time-resolved exciton luminescence in GaAs/AlGaAs quantum wires and dots

1995 ◽  
Vol 17 (2) ◽  
pp. 201-212 ◽  
Author(s):  
Yong Zhang ◽  
M.D. Sturge ◽  
K. Kash ◽  
B.P. van der Gaag ◽  
A.S. Gozdz ◽  
...  
Keyword(s):  
Quantum Wires ◽  
Exciton Luminescence ◽  
Temperature Dependent ◽  
Time Resolved
Sign in / Sign up

Export Citation Format

Share Document