Dielectric Behavior of CVD (Ba,Sr)TiO3 thin Films on Pt/Si

1995 ◽  
Vol 415 ◽  
Author(s):  
S.K. Streiffer ◽  
C. Basceri ◽  
A.I. Kingon ◽  
S. Lipa ◽  
S. Bilodeau ◽  
...  
Keyword(s):  
Thin Films ◽  
Carrier Transport ◽  
Low Frequency ◽  
Chemical Vapor ◽  
Frequency Dispersion ◽  
Dielectric Behavior ◽  
Polarization Current ◽  
Low Dissipation ◽  
Frequency Independent ◽  
The Time Domain

ABSTRACTWe have investigated the dielectric behavior of polycrystalline (Ba,Sr)TiO3 thin films deposited by liquid-source metalorganic chemical vapor deposition. The time-domain polarization current, the frequency dependence of the permittivity, and the dielectric loss for these CVD films are all described by a single set of parameters via the phenomenology of Curie - von Schweidler behavior. No change in the general form of the permittivity is found out to 1.5 GHz, suggesting that this description of the response is valid into the frequency range of interest for many applications. Low-frequency dispersion is found to be controllable, leading to films with very low dissipation factors and almost frequency-independent dielectric response. Finally, a non-zero intercept of the inverse of capacitance versus film thickness suggests the existence of a series interfacial capacitance, arising from either microstructural inhomogeneity or energy barriers to carrier transport at the film-electrode interfaces.

Comparative Study of Photocarrier Dynamics in CVD-deposited CuWO4, CuO, and WO3 Thin Films for Photoelectrocatalysis

2020 ◽  
Vol 234 (4) ◽  
pp. 699-717
Author(s):  
James Hirst ◽  
Sönke Müller ◽  
Daniel Peeters ◽  
Alexander Sadlo ◽  
Lukas Mai ◽  
...  
Keyword(s):  
Thin Films ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Terahertz Spectroscopy ◽  
Chemical Vapor ◽  
Photoelectrochemical Cells ◽  
Time Resolved ◽  
And Diffusion ◽  
Wo3 Thin Films ◽  
Carrier Transport Properties

AbstractThe temporal evolution of photogenerated carriers in CuWO4, CuO and WO3 thin films deposited via a direct chemical vapor deposition approach was studied using time-resolved microwave conductivity and terahertz spectroscopy to obtain the photocarrier lifetime, mobility and diffusion length. The carrier transport properties of the films prepared by varying the copper-to-tungsten stoichiometry were compared and the results related to the performance of the compositions built into respective photoelectrochemical cells. Superior carrier mobility was observed for CuWO4 under frontside illumination.

DIELECTRIC PROPERTIES OF DRY, GEOLOGIC MATERIALS

Geophysics ◽  
1970 ◽  
Vol 35 (4) ◽  
pp. 624-645 ◽  
Author(s):  
M. Saint‐Amant ◽  
David W. Strangway
Keyword(s):  
Dielectric Properties ◽  
Loss Tangent ◽  
Relaxation Times ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Relaxation Peak ◽  
Debye Relaxation ◽  
Thermally Activated ◽  
Geologic Materials ◽  
Frequency Independent

A detailed investigation of the dielectric properties of powdered and solid dry rocks in the frequency range of 50 hz to 2 mhz has revealed the following general characteristics: 1) All dry rocks, powdered and solid, show an increase in both the dielectric constant and the loss tangent as frequency decreases and as temperature increases. This dispersion is believed to be due to polarization associated with charge buildup at grain boundaries or at grain imperfections. 2) Dry powdered rocks often show a thermally‐activated relaxation peak with a typical Debye‐relaxation character. This is due to the presence of pyroxene and biotite and may be associated with other minerals. The relaxation peak is not seen in solid rocks, where it is hidden by the low‐frequency dispersion. 3) At high frequencies, the loss tangent approaches a constant value which is frequency independent. This behavior is observed in many dielectrics and may be the result of a distribution of relaxation times.

Ferroelectric Properties of La-doped Bi4Ti3O12 Thin Films deposited directly on Si by pulse-injection MOCVD

2000 ◽  
Vol 655 ◽  
Author(s):  
Joon Hyeong Kim ◽  
Jin Young Kim ◽  
Hyeong Joon Kim
Keyword(s):  
Thin Films ◽  
Metalorganic Chemical Vapor Deposition ◽  
Ferroelectric Properties ◽  
Low Frequency ◽  
Chemical Vapor ◽  
Amorphous Layer ◽  
Frequency Region ◽  
Pulse Injection ◽  
Ferroelectric Hysteresis ◽  
La Doped

Abstract(Bi,La)4Ti3O12(BLT) thin films were prepared on Si(100) substrates by the pulse injection metalorganic chemical vapor deposition (MOCVD) process, in which Ti and La precursors were injected with periodic pauses while Bi precursor was supplied continuously. In case of the pulse injection method, the film composition was relatively uniform and the Bi content at the interface was relatively uniform and the Bi content at the interface was increased. The BLT films, which were deposited by the pulse injection MOCVD, showed better crystallinity and thinner ionterfacial amorphous layer than the continuous BLT films. The continuous BLT films, although measured at 1 MHz showed similar C-V characteristics to those measured at low frequency region, and their flatband voltages also shifted severely to the negative voltage direction. On the other hand, the pulse BLT films exhibited clockwise ferroelectric hysteresis in the C-V curves. The memory window and the leakage current density were about 2V and 1.46×10−7 A/cm2 at 9V (180 kV/cm), respectively.

Low frequency dispersion in GaSe thin films

1996 ◽  
Vol 280 (1-2) ◽  
pp. 262-264 ◽  
Author(s):  
M.K. Anis ◽  
M.S. Khan ◽  
H. Asim
Keyword(s):  
Thin Films ◽  
Low Frequency ◽  
Frequency Dispersion

Study of Thin Film Ferroelectric Superlattices

1996 ◽  
Vol 433 ◽  
Author(s):  
Y. Kim ◽  
A. Erbil ◽  
E.W. Thomas ◽  
A. Kushwaha ◽  
R. Gerhardt
Keyword(s):  
Thin Films ◽  
Lead Titanate ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Dielectric Behavior ◽  
Prism Coupler ◽  
Compositional Modulation ◽  
Device Applications ◽  
Secondary Ion ◽  
Mocvd Technique

AbstractThe study of ferroelectric thin films has evoked special interest owing to their numerous applications. In this study, epitaxial or highly oriented PbTiO3/PLT (Lead Titanate / La modified Lead Titanate) ferroelectric superlattice thin films were grown by the metalorganic chemical vapor deposition (MOCVD) technique. Compositional modulation by Secondary Ion Mass Spectroscopy (SIMS) established the nature of these films as desirable for high quality device applications. The thickness and the refractive index of each film was determined by using a prism coupler. The dielectric behavior of these films was studied as a function of frequency.

Improving contact performance of graphene on p-type GaN thin films with V-pits microstructures

2018 ◽  
Vol 32 (19) ◽  
pp. 1840052
Author(s):  
Ruo-Nong Song ◽  
Wen-Cheng Ke
Keyword(s):  
Thin Films ◽  
Ohmic Contact ◽  
Carrier Transport ◽  
Single Layer ◽  
Chemical Vapor ◽  
Single Layer Graphene ◽  
Visible Range ◽  
Organic Chemical ◽  
Metal Organic ◽  
P Type

This study presents the electrical properties of graphene that directly is contact on two types of p-type GaN thin films. The diameter of several hundred nanometer V-pits were formed on the p-GaN thin films by adjusting the NH3 flow rate during the metal organic chemical vapor deposition epitaxial process. The single-layer graphene with a high transmittance of 97% in the visible range was transferred on p-GaN thin films to form an Ohmic contact. The V-pits provide more carrier transport paths that promote the carrier tunneling into p-GaN thin films, resulting in a better Ohmic contact performance. In addition, the increased current value was attributed to the presence of V-pits on the p-GaN thin films.

Dielectric Behavior of PVDF/PP-PT Nanocomposite Thin Films

2014 ◽  
Vol 1002 ◽  
pp. 11-16
Author(s):  
Ting Ting Yu ◽  
Zhao Hui Ren ◽  
Si Min Yin ◽  
Xin Yang ◽  
Yi Feng Yu ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Low Frequency ◽  
Weight Ratio ◽  
Dielectric Behavior ◽  
Β Phase ◽  
Nanocomposite Thin Films ◽  
Coating Method

PVA/PVP-assisted hydrothermal method was used to prepare single-crystal pre-perovskite PbTiO3(PP-PT) nanofibers, in which polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) acted as surfactants. Subsequently, poly (vinylidene fluoride)/ pre-perovskite PbTiO3nanofibers (PVDF/PP-PT) nanocomposite thin films were successfully fabricated by a spin-coating method. The test results showed that PP-PT nanofibers had a good distribution in PVDF matrix. Moreover, α-phase coexisted with β-phase in the PVDF and PVDF/PP-PT nanocomposite thin films. The dielectric properties of the PVDF/PP-PT nanocomposite thin films were measured as a function of frequency in the range of 5 kHz to 5 MHz. It is worth noting that the dielectric constant of nanocomposite thin films increased with increasing the weight ratio of PP-PT nanofibers in the low frequency range. By contrast, the dielectric constant of PVDF/PP-PT nanocomposite thin film which contained 20% PP-PT nanofibers was 43.7% larger than that of pure PVDF thin film (εr= 6.77) at 5 kHz, and the loss tangent was ~0.03.

Effect of Nature of the Precursor on Crystallinity and Microstructure of MOCVD-Grown ZrO2 Thin Films

2002 ◽  
Vol 745 ◽  
Author(s):  
M. S. Dharmaprakash ◽  
S. A. Shivashankar
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Dielectric Behavior ◽  
Film Deposition ◽  
Molecular Structures ◽  
Cubic Phase ◽  
Zirconium Complexes ◽  
Substrate Temperatures

ABSTRACTIn the present work, we report the deposition of zirconia thin films on Si(100) at various substrate temperatures by low-pressure metalorganic chemical vapor deposition (MOCVD). Three different zirconium complexes, viz., tetrakis(2,4-pentadionato)zirconium(IV), [Zr(pd)4], tetrakis(2,2,6,6-tetramethyl-3,5-heptadionato)zirconium(IV), [Zr(thd)4], and tetrakis(t-butyl-3-oxo-butanoato)zirconium(IV), [Zr(tbob)4] are used as precursors. The relationship between the molecular structures of the precursors and their thermal properties, as examined by TG/DTA is presented. The films deposited using these precursors have distinctly different morphology, though all of them are of the cubic phase. The films grown from Zr(thd)4 are well crystallized, showing faceted growth at 575°C, whereas the films grown from Zr(pd)4 and Zr(tbob)4 are not well crystallized, and display cracks. These differences in the observed microstructure may be attributed to the different chemical decomposition pathways of the precursors during the film growth, which influence the nucleation and the growth processes. This is also evidenced by the different kinetics of growth from these three precursors under otherwise identical CVD conditions. The details of thin film deposition, and film microstructure analysis by XRD and SEM is presented. The dielectric behavior of the films deposited from different precursors, as studied by C-V measurements, are compared.

Sign in / Sign up

Export Citation Format

Share Document