scholarly journals Terahertz Emission Spectroscopy and Microscopy on Ultrawide Bandgap Semiconductor β-Ga2O3

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 73
Author(s):  
Hao Jiang ◽  
Chen Gong ◽  
Tatsuhiko Nishimura ◽  
Hironaru Murakami ◽  
Iwao Kawayama ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Time Derivative ◽  
Beam Diameter ◽  
Band Bending ◽  
Fs Laser ◽  
Band Transition ◽  
Photo Response ◽  
Terahertz Emission Spectroscopy ◽  
And Diffusion

Although gallium oxide Ga2O3 is attracting much attention as a next-generation ultrawide bandgap semiconductor for various applications, it needs further optical characterization to support its use in higher-performance devices. In the present study, terahertz (THz) emission spectroscopy (TES) and laser THz emission microscopy (LTEM) are applied to Sn-doped, unintentionally doped, and Fe-doped β-Ga2O3 wafers. Femtosecond (fs) laser illumination generated THz waves based on the time derivative of the photocurrent. TES probes the motion of ultrafast photocarriers that are excited into a conduction band, and LTEM visualizes their local spatiotemporal movement at a spatial and temporal resolution of laser beam diameter and a few hundred fs. In contrast, one observes neither photoluminescence nor distinguishable optical absorption for a band-to-band transition for Ga2O3. TES/LTEM thus provides complementary information on, for example, the local mobility, surface potential, defects, band bending, and anisotropic photo-response in a noncontact, nondestructive manner. The results indicated that the band bends downward at the surface of an Fe-doped wafer, unlike with an n-type wafer, and the THz emission intensity is qualitatively proportional to the product of local electron mobility and diffusion potential, and is inversely proportional to penetration depth, all of which have a strong correlation with the quality of the materials and defects/impurities in them.

Ultrafast Laser Cleaning of Daguerreotypes

2011 ◽  
Vol 1319 ◽  
Author(s):  
Michael J. Abere ◽  
Ryan D. Murphy ◽  
Bianca Jackson ◽  
Gerard Mourou ◽  
Michel Menu ◽  
...  
Keyword(s):  
Material Removal ◽  
Silver Oxide ◽  
Laser Pulses ◽  
Silver Sulfide ◽  
Ultrafast Laser ◽  
Beam Diameter ◽  
Chemical Cleaning ◽  
Silver Substrate ◽  
Fs Laser ◽  
Lower Material

ABSTRACTAn ultrafast laser irradiation method for the removal of corrosion from Daguerreotypes without detrimentally affecting image quality has been developed. Corrosion products such as silver oxide and silver sulfide may be removed by chemical cleaning but these reactions are hard to control and are often damaging to the underlying silver, ruining the image. The Ti:Sapphire 150 fs laser pulses used in this study are focused to a beam diameter of 60 μm and are normally incident to the Daguerreotype. It was found that the corrosion layer has a lower material removal threshold than silver allowing for removal of corrosion with minimal removal of vital information contained in the silver substrate.

Studies of interface polarization and magnetization dynamics using terahertz emission spectroscopy

2005 ◽  
Author(s):  
Shayne M. Harrel ◽  
James M. Schleicher ◽  
Eric Beaurepaire ◽  
Jean-Yves Bigot ◽  
Charles A. Schmuttenmaer
Keyword(s):  
Emission Spectroscopy ◽  
Magnetization Dynamics ◽  
Terahertz Emission ◽  
Interface Polarization ◽  
Terahertz Emission Spectroscopy

Helicity-dependent photocurrent in a Bi2Se3 thin film probed by terahertz emission spectroscopy

2016 ◽  
Vol 94 (16) ◽  
Author(s):  
Sun Young Hamh ◽  
Soon-Hee Park ◽  
Sahng-Kyoon Jerng ◽  
Jae Ho Jeon ◽  
Seung-Hyun Chun ◽  
...  
Keyword(s):  
Thin Film ◽  
Emission Spectroscopy ◽  
Terahertz Emission ◽  
Terahertz Emission Spectroscopy

scholarly journals Well-posedness and long-time behavior for the modified phase-field crystal equation

2014 ◽  
Vol 24 (14) ◽  
pp. 2743-2783 ◽  
Author(s):  
Maurizio Grasselli ◽  
Hao Wu
Keyword(s):  
Phase Field ◽  
Time Derivative ◽  
Exponential Attractor ◽  
Well Posedness ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Long Time ◽  
Global Existence And Uniqueness ◽  
And Diffusion ◽  
Phase Field Crystal

We consider a modification of the so-called phase-field crystal (PFC) equation introduced by K. R. Elder et al. This variant has recently been proposed by P. Stefanovic et al. to distinguish between elastic relaxation and diffusion time scales. It consists of adding an inertial term (i.e. a second-order time derivative) into the PFC equation. The mathematical analysis of the resulting equation is more challenging with respect to the PFC equation, even at the well-posedness level. Moreover, its solutions do not regularize in finite time as in the case of PFC equation. Here we analyze the modified PFC (MPFC) equation endowed with periodic boundary conditions. We first prove the global existence and uniqueness of a solution with initial data in a bounded energy space. This solution satisfies some uniform dissipative estimates which allow us to study the long-time behavior of the corresponding dynamical system. In particular, we establish the existence of the global attractor as well as an exponential attractor. Then we demonstrate that any trajectory originating from the bounded energy phase space converges to a single equilibrium. This is done by means of a suitable version of the Łojasiewicz–Simon inequality. An estimate on the convergence rate is also given.

scholarly journals Determination of the time origin by 
the maximum entropy method in 
time-domain terahertz emission spectroscopy

2010 ◽  
Vol 18 (15) ◽  
pp. 15853 ◽  
Author(s):  
Takeya Unuma ◽  
Yusuke Ino ◽  
Makoto Kuwata-Gonokami ◽  
Erik M. Vartiainen ◽  
Kai-Erik Peiponen ◽  
...  
Keyword(s):  
Maximum Entropy ◽  
Time Domain ◽  
Emission Spectroscopy ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Terahertz Emission ◽  
Terahertz Emission Spectroscopy ◽  
Time Origin

Characterization of Magnetization Dynamics using Terahertz Emission Spectroscopy

2007 ◽  
pp. 793-795
Author(s):  
James M. Schleicher ◽  
Shayne M. Harrel ◽  
Charles A. Schmuttenmaer ◽  
Eric Beaurepaire ◽  
Jean-Yves Bigot
Keyword(s):  
Emission Spectroscopy ◽  
Magnetization Dynamics ◽  
Terahertz Emission ◽  
Terahertz Emission Spectroscopy

Environmental Factors

2020 ◽  
Vol 16 (4) ◽  
pp. 58-72
Author(s):  
Violah Mpangwire ◽  
Annabella Ejiri Habinka ◽  
Fred Kaggwa
Keyword(s):  
Environmental Factors ◽  
Diffusion Of Innovation ◽  
Innovation Adoption ◽  
Government Support ◽  
Identification System ◽  
Perceived Trust ◽  
Good Government ◽  
Effectiveness And Efficiency ◽  
And Diffusion

The use of the unified identification system (UIDS) can undoubtedly result in increased effectiveness and efficiency, improvement in the quality of life, reduction of crime, enhanced transparency, and good government. This study examined the dimensions of environmental factors in explaining the adoption of a unified identification system (UIDS). Dynamic capability theory (DCT), technology- organisation-environment (TOE) framework, and diffusion of innovation (DOI) were used as grounding theories. The study opted for a concurrent triangulation research design. The results revealed that government support, competitive pressure, and perceived trust are significant and support the adoption of a unified identification system. However, user readiness was insignificant in explaining the use of UIDS in the Ugandan context. This study recommends that policymakers focus on government support as it is a symbol of leadership in IS innovation adoption.

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