Time-domain Terahertz Spectroscopy of Strontium Bismuth Tantalate Thin Films

2003 ◽  
Vol 784 ◽  
Author(s):  
K. Kotani ◽  
M. Misra ◽  
I. Kawayama ◽  
M. Tonouchi
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Ferroelectric Material ◽  
Frequency Region ◽  
Frequency Range ◽  
The Difference ◽  
Dielectric And Optical Properties ◽  
Mgo Substrate

ABSTRACTWe have measured the dielectric and optical properties of pulsed laser deposited SrBi2Ta 2O9 and Sr0.8Bi2.2Ta2O9 thin films on MgO substrate in THz frequency region by THz time-domain spectroscopy. The imaginary parts of the dielectric constant of both the samples show broad peaks in the frequency range 0.5–1.0 THz, which may be due to the soft mode in SBT in this frequency spectrum. The difference in the real part of the dielectric constant of Sr0.8Bi2.2Ta2O9 thin films is small for MHz and THz frequencies. On the other hand, the value of real part of dielectric constant of SrBi2Ta2O9 thin films in THz frequency range is much smaller than that in MHz frequency region, indicating that SrBi2Ta2O9 is not simply displacive ferroelectric material.

TRANSPORT PROPERTIES OF THERMALLY EVAPORATED In2Se3 THIN FILMS

2009 ◽  
Vol 16 (05) ◽  
pp. 723-729 ◽  
Author(s):  
D. NITHYAPRAKASH ◽  
B. PUNITHAVENI ◽  
J. CHANDRASEKARAN
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Ac Conductivity ◽  
Thermal Evaporation ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Cbh Model ◽  
X Ray ◽  
Correlated Barrier Hopping ◽  
Tan Δ

Thin films of In2Se3 were prepared by thermal evaporation. X-ray diffraction indicated that the as-grown films were amorphous in nature and became polycrystalline γ-In2Se3 films after annealing. The ac conductivity and dielectric properties of In2Se3 films have been investigated in the frequency range 100 Hz–100 kHz. The ac conductivity σ ac is found to be proportional to ωn where n < 1. The temperature dependence of both ac conductivity and the parameter n is reasonably well interpreted by the correlated barrier hopping (CBH) model. The values of dielectric constant ε and loss tangent tan δ were found to increase with frequency and temperature. The ac conductivity of the films was found to be hopping mechanism. In I–V characteristic for different field and temperature were studied and it has been found that the conduction process is Poole–Frenkel type.

scholarly journals Broadband Terahertz Light-Matter Interaction Enhancement for Precise Spectroscopy of Thin Films and Micro-Samples

2018 ◽  
Author(s):  
Romain Peretti ◽  
Flavie Braud ◽  
Emilien Peytavit ◽  
Emmanuel Dubois ◽  
Jean-François Lampin
Keyword(s):  
Thin Films ◽  
Water Absorption ◽  
Time Domain ◽  
Terahertz Spectroscopy ◽  
Broad Band ◽  
Sample Volume ◽  
Vibrational States ◽  
Dna And Rna ◽  
Matter Interaction ◽  
Light Matter Interaction

In biology molecules and macromolecules like sugars, proteins, DNA, and RNA are of utter importance. Detecting their presence as well as their conformation is still a challenge in many cases. It is well known that the vibrational states of such molecules lie from the infrared to the TeraHertz range. Spectroscopy can be used to detect such compounds and probe their conformation. Still, terahertz spectroscopy on biosample is a challenge for two main reasons: water absorption; and the small size of the samples. The sample volume is smaller than the cube of the TeraHertz wavelength; the light matter interactions are thus extremely reduced. In this paper, we present the design, fabrication, characterization and the first typical uses of a biophotonic device aiming at increasing light matter interaction to enable terahertz spectroscopy of minute samples on a broad band (0.2&ndash;2 THz). We demonstrate time domain spectroscopy experiments on few &micro;l samples showing the validity of our approach.

Measurement of the dielectric constant of thin films by terahertz time-domain spectroscopic ellipsometry

2011 ◽  
Vol 36 (2) ◽  
pp. 265 ◽  
Author(s):  
Naoki Matsumoto ◽  
Tadasu Hosokura ◽  
Takeshi Nagashima ◽  
Masanori Hangyo
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Spectroscopic Ellipsometry ◽  
Time Domain

scholarly journals Complex Refractive Index of Strontium Titanate in the Terahertz Frequency Range

2019 ◽  
Vol 7 (4) ◽  
pp. 71-80 ◽  
Author(s):  
V. R. Bilyk ◽  
K. A. Grishunin
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Strontium Titanate ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Complex Dielectric Constant ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Time Domain Spectroscopy ◽  
Terahertz Frequency Range

The recent progress in terahertz time-domain spectroscopy enables the accurate and reliable measurements of dielectric properties in comparison with the traditional far-infrared spectroscopy using an incoherent light source. The broadband THz-TDS is a powerful tool to determine the real and imaginary parts of a complex dielectric constant by the transmission which allows to detect the parameters of the soft modes in ferroelectrics. In this work, the terahertz time-domain spectroscopy was used to investigate the dependence of the complex refractive index of a single-crystal quantum paraelectric strontium titanate in the terahertz frequency range from 0.3 to 2 THz. It was shown that the low-frequency terahertz response of the material is determined by the soft phonon mode TO1. The measured experimental dependences showed a good agreement with the theoretical curves obtained from the analysis of the Lorentz oscillator model for the complex dielectric constant of strontium titanate. The obtained results are necessary for understanding the principle of possibility to manipulate the order parameter in ferroelectric materials and can be used to create energy-efficient memory devices with a speed of recording information close to the theoretical limit.

Research on the Signal Encrypted by Unary Polynomial Transformation Chaos

2013 ◽  
Vol 846-847 ◽  
pp. 952-955
Author(s):  
Ling Wu ◽  
Hong Chen ◽  
Shu Bin Gu ◽  
Lian Dong Lin ◽  
Guo Qiang Lan
Keyword(s):  
Time Domain ◽  
Low Frequency ◽  
Chaotic Signal ◽  
Frequency Region ◽  
Simulation Environment ◽  
Matlab Simulation ◽  
Frequency Range ◽  
Frequency Signal ◽  
Polynomial Transformation ◽  
Narrow Area

In terms of the chaotic signal needed by encryption, it is the more complicate the better. In addition, the frequency range of chaos should be wider than that of signal to be encrypted. However, chaotic spectrum usually is a narrow area in the low frequency region, and the complexity is not high enough. The signals encryption effects are affected. In order to solve this problem, this paper used the chaos transformed by unary polynomial to encrypt signals. Under the Matlab simulation environment, it is confirmed from time-domain and frequency-domain perspectives that the encryption effect of transformed chaos is better. Even the higher frequency signal can also be covered up completely. At the same time, the difficulty of decoding the encrypted signals is greatly increased, and the anti-attacking capability is strengthened.

Time-domain dielectric constant measurement of thin film in GHz–THz frequency range near the Brewster angle

1999 ◽  
Vol 74 (15) ◽  
pp. 2113-2115 ◽  
Author(s):  
M. Li ◽  
G. C. Cho ◽  
T.-M. Lu ◽  
X.-C. Zhang ◽  
S.-Q. Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Time Domain ◽  
Brewster Angle ◽  
Frequency Range ◽  
Constant Measurement ◽  
Dielectric Constant Measurement

Relative dielectric constant of epitaxial BaTiO3 thin films in the GHz frequency range

2003 ◽  
Vol 83 (25) ◽  
pp. 5274-5276 ◽  
Author(s):  
T. Hamano ◽  
D. J. Towner ◽  
B. W. Wessels
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Relative Dielectric Constant ◽  
Frequency Range
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