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1.
Pasquale D’Angelo Pablo Stoliar Tobias Cramer Antonio Cassinese Francesco Zerbetto Fabio Biscarini 《Applied Physics A: Materials Science & Processing》2009,95(1):55-60
A dynamic method for quantifying the amount and mechanism of trapping in organic field effect transistors (OFETs) is proposed.
It exploits transfer characteristics acquired upon application of a triangular waveform gate sweep V
G. The analysis of the transfer characteristics at the turning point V
G=−V
max between forward and backward gate sweeps, viz. around the maximum gate voltage V
max applied, provides a differential slope Δm which depends exclusively on trapping. Upon a systematic change of V
max it is possible to extract the initial threshold voltage, equivalent to one of the observables of conventional stress measurements,
and assess the mechanism of trapping via the functional dependence on the current. The analysis of the differential logarithmic
derivative at the turning point yields the parameters of trapping, as the exponent β and the time scale of trapping τ. In the case of an ultra-thin pentacene OFET we extract β=1 and τ=102–103 s, in agreement with an exponential distribution of traps. The analysis of the hysteresis parameter Δm is completely general and explores time scales much shorter than those involved in bias stress measurements, thus avoiding
irreversible damage to the device. 相似文献
2.
Pankaj Kumar S. C. Jain Vikram Kumar Suresh Chand R. P. Tandon 《Applied Physics A: Materials Science & Processing》2009,94(2):281-286
Current–voltage (J–V) characteristics of organic bulk heterojunction diodes based on an interpenetrating network of poly(3-hexylthiophene) (P3HT)
and [6,6]-phenyl C61-butyric acid methyl esters (PCBM) have been studied in the dark and under halogen lamp illumination. The diodes contained
1:1 and 1:0.6 weight ratios of P3HT and PCBM. For both diodes the currents measured in dark (J
d
, commonly known as the dark current) in forward bias are found to agree with the space charge limited current (SCLC). The
illuminated current consists of a current due to applied voltage (J
da
) and the light generated current (J
L
). J
da
extracted from the illuminated current agrees well with Shockley’s diffusion and recombination current. This observation
shows that illumination changes the SCLC into Shockley’s diffusion and recombination current. The forward current under illumination
has been observed to be greater than the dark current, which is contrary to the photo–voltaic (PV) theory. This result is
well explained by the change of SCLC into Shockley’s diffusion and recombination current.
Former address of S.C. Jain: IMEC, Kapeldreef 75, 3001 Leuven, Belgium. 相似文献
3.
An experimental analysis is presented to correlate the secondary dendrite arm spacing λ
2 and dendrite tip radius R with growth rate V and Mg content C
0-Mg of Al–Cu–Mg ternary alloys. Under constant temperature gradient G (4.84±0.13 K mm−1), a series of directional solidification experiments were performed at five different growth rates V (16.7–83.3 μm/s) and five different Mg contents C
0-Mg in Al–5 wt.% Cu–(0.5–5) wt.% Mg alloys. Solid–liquid interface was investigated from the longitudinal sections of the quenched
samples, and λ
2 and R were measured on the dendrite tips. The dependencies of λ
2 and R on V and C
0-Mg were determined. The experimental results showed that the values of λ
2 and R decrease as V and C
0-Mg increase at a constant G. The present exponent values related to V are found to be slightly lower than the values of the theoretical models and previous experimental works; however, C
0-Mg exponent values are found to be much lower than the theoretical models and previous experimental works. The ratio of the
secondary dendrite arm spacing to the dendrite tip radius is 2.09±0.15, in good agreement with the scaling law. At a constant
C
0-Mg, the values of VR
2 were found to slightly increase with the ascending V. However, as C
0-Mg increases, the values of VR
2 decrease. 相似文献
4.
J. P. Xu X. Zou C. X. Li P. T. Lai C. L. Chan 《Applied Physics A: Materials Science & Processing》2009,94(2):419-422
Reactive cosputtering is employed to prepare high-permittivity HfTiO gate dielectric on n-Ge substrate. Effects of Ge-surface
pretreatment on the interface and gate leakage properties of the dielectric are investigated. Excellent performances of Al/HfTiO/GeO
x
N
y
/n-Ge MOS capacitor with wet–NO surface pretreatment have been achieved with a interface-state density of 2.1×1011 eV−1 cm−2, equivalent oxide charge of −7.67×1011 cm−2 and gate leakage current density of 4.97×10−5 A/cm2 at V
g
=1 V. 相似文献
5.
Giant magnetoresistance in Hg
1−x−y
Mn
x
Fe
y
Te crystals is caused by clusters with “antiferromagnetic” (Mn-Te-Mn-Te, Mn-Te-Fe-Te) and “ferromagnetic” (Fe-Fe-Fe) ordering. The effect is due to the fact that the charge carriers taking part in electric current interact with the “ferromagnetic”
cluster subsystem (Fe-Fe-Fe) magnetized to saturation and become spin-polarized. These spin-polarized charge carriers are strongly scattered by the “antiferromagnetic”
Mn-Te-Mn-Te and Mn-Te-Fe-Te clusters, because the magnetic moments inside the clusters and resultant moments of clusters have chaotic orientations. Investigations
of kinetic coefficients of Hg
1−x−y
Mn
x
Fe
y
Te crystals before and after thermal treatment show that there is no marked correlation between the giant magnetoresistance
and charge-carrier concentration, mobility, and band parameters of crystals.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 28–33, October, 2007. 相似文献
6.
R. Weißmann R. Koschatzky W. Schnellhammer K. Müller 《Applied Physics A: Materials Science & Processing》1977,13(1):43-46
Auger electron spectra of the transition metals Cr, Mn, Fe, Co and Ni as well as their oxides have been investigated in the
energy range between 0–100 eV. In each case of the clean metal surface the observed spectrum consists essentially of one Auger
line identified asM
2,3
VV transition. After oxidation a line doublet is observed revealing two transitions instead of one. Additional new Auger peaks
appear in the low energy range between 0–30 eV. The “splitting” of the Auger line can be explained as resulting from aM
2,3
V
dVd and aM
2,3
V
pVp transition. The latter is characteristic for the compound and can in a simple way be interpreted as a cross transition. 相似文献
7.
N. N. Loshkareva Yu. P. Sukhorukov S. V. Naumov N. I. Solin I. B. Smolyak E. V. Panfilova 《JETP Letters》1998,68(1):97-100
In a study of the infrared optical absorption spectra of polycrystalline La1−x
CaxMnO3 (0.1⩽x⩽0.8), a contribution from free charge carriers is observed below the Curie temperature for compositions with x⩽0.4. The existence of this contribution for samples with a high resistivity is a direct proof of the existence of “metallic”
drops in an insulating matrix. The relative volume of the “metallic” phase is estimated.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 89–92 (10 July 1998) 相似文献
8.
J. M. J. Lopes U. Littmark M. Roeckerath E. Durun ?zben S. Lenk U. Breuer A. Besmehn A. St?rk P. L. Grande M. A. Sortica C. Radtke J. Schubert S. Mantl 《Applied Physics A: Materials Science & Processing》2009,96(2):447-451
The influence of post-deposition oxygen anneals on the properties of amorphous LaScO3 films on Si(100) is reported. The use of an isotopically (18O2) enriched atmosphere allowed to investigate the 16O–18O exchange and the oxygen diffusion across the dielectric layer. Such effects are connected to the formation of an interfacial
layer. Oxygen annealing leads to nearly ideal capacitance–voltage curves, lower leakage currents and interface trap densities,
as well as to κ-values up to 33 for the LaScO3 films. These results are attributed to the suppression of oxygen-related trap centers and the achievement of a stoichiometric
oxygen content. 相似文献
9.
U. Kreibig 《Applied physics. B, Lasers and optics》2008,93(1):79-89
Surface and, in particular, interface effects influence all physical and chemical properties of nanostructured matter. Mie
surface plasmon polaritons (MPPs) in metallic nanoparticles are excellent and sensitive sensors for optical investigation
of these effects of realistic particles since their lifetimes due to dephasing (decoherence) effects and their resonance energies
drastically depend upon the chemistry and topology of their surfaces/interfaces. A survey is given over some results of our
own long term research on MPPs which started, in fact, as early as 1969. Theoretical models and experiments concerning the
A parameter, the δ
n parameter, MPP phase decoherence and static and dynamic interface charge transfer effects (“chemical interface damping”)
are briefly summarized. The effect of radiation damping is disregarded throughout: we assume the particle sizes to be small
enough to justify this simplification, which makes it easier to draw conclusions from the MPPs on nanomaterial properties.
Obviously, there is a wide field for future research concerning particle interfaces on the basis of Mie’s theory. On the other
hand, all of these effects have to be incorporated into Mie’s theory to obtain a “modern” version which is reliable on a quantitative
level to describe experimental data. 相似文献
10.
A. V. Voitsekhovskii S. N. Nesmelov S. M. Dzyadukh V. S. Varavin S. A. Dvoretskii N. N. Mikhailov Yu. G. Sidorov 《Russian Physics Journal》2011,54(3):263-270
The effect of regions with periodic sharp 48–54 nm thick inhomogeneities in composition on the electrophysical characteristics
of MIS structures based on graded-gap n-Hg1–x
Cd
x
Te (x = 0.29–0.31) grown by molecular-beam epitaxy is studied. It is found that major electro-physical and photo-electrical
characteristics are qualitatively similar for MIS structures based on n-Hg1–x
Cd
x
Te with sharp inhomogeneities in composition (barriers) and without “barriers”. It is shown that the electrical characteristics
are mostly affected by the “barrier regions” located close to the insulator – semiconductor interface. This effect is manifested
in an increase of the effective dielectric thickness, which can be due to the fact that the regions of enhanced composition
form potential barriers for electrons, and in a decrease in the relaxation time of non-equilibrium carriers due to recombination
at the boundaries of the regions with sharp changes in composition. 相似文献
11.
The model considered here is the “jellium” model in which there is a uniform, fixed background with charge density −eρ in a large volume V and in which N=ρV particles of electric charge +e and mass m move – the whole system being neutral. In 1961 Foldy used Bogolubov's 1947 method to investigate the ground state energy
of this system for bosonic particles in the large ρ limit. He found that the energy per particle is −0.402 in this limit, where . Here we prove that this formula is correct, thereby validating, for the first time, at least one aspect of Bogolubov's pairing
theory of the Bose gas.
Received: 23 August 2000 / Accepted: 5 October 2000 相似文献
12.
E. Abad J. Ortega Y. J. Dappe F. Flores 《Applied Physics A: Materials Science & Processing》2009,95(1):119-124
A local orbital DFT-approach combined with a “scissor”-operator is used to obtain the Charge Neutrality Level and the screening
parameter in the benzene/Au(111) and C60/Au(111) interfaces. The “pillow” dipole and interface Fermi level are also calculated. The total dipole induced across the
interface is compared with the experimental evidences: while the agreement for C60/Au(111) is excellent, for benzene/Au(111), some discrepancies appear that are discussed in the light of other models. 相似文献
13.
Verneuil E Clain J Buguin A Brochard-Wyart F 《The European physical journal. E, Soft matter》2003,10(4):345-353
A soft bead (radius R
b) is pressed with a force F against a hydrophobic glass plate through a water drop (“wet” JKR set-up). We observe with a fast camera the growth of the
contact zone bridging the rubber bead to the glass. Depending on the approach velocity V, two regimes are observed : i) at large V a liquid film is squeezed at the interface and dewets by nucleation and growth of a dry contact; ii) at low velocities, the
bead remains nearly spherical. As it comes into contact, the rubber bead spreads on the glass with a characteristic time (in
the range of one millisecond) τ ≈ ηR
b
2/F, where η is the liquid viscosity. The laws of spreading are interpreted by a balance of global mechanical and viscous forces.
Received: 22 December 2002 / Accepted: 24 March 2003 / Published online: 29 April 2003
RID="a"
ID="a"e-mail: brochard@curie.fr 相似文献
14.
T. Mills L. G. Kaake X.-Y. Zhu 《Applied Physics A: Materials Science & Processing》2009,95(1):291-296
Electrolytes are finding applications as dielectric materials in low-voltage organic thin-film transistors (OTFT). The presence
of mobile ions in these materials (polymer electrolytes or ion gels) gives rise to very high capacitance (>10 μF/cm2) and thus low transistor turn-on voltage. In order to establish fundamental limits in switching speeds of electrolyte gated
OFETs, we carry out in situ optical spectroscopy measurement of a poly(3-hexylthiophene) (P3HT) OTFT gated with a LiClO4:poly(ethyleneoxide) (PEO) dielectric. Based on spectroscopic signatures of molecular vibrations and polaron transitions,
we quantitatively determine charge carrier concentration and diffusion constants. We find two distinctively different regions:
at V
G≥−1.5 V, drift-diffusion (parallel to the semiconductor/dielectric interface) of hole-polarons in P3HT controls charging of
the device; at V
G<−1.5 V, electrochemical doping of the entire P3HT film occurs and charging is controlled by drift/diffusion (perpendicular
to the interface) of ClO4
− counter ions into the polymer semiconductor. 相似文献
15.
E. Glickman D. Fuks N. Frage S. Barzilai N. Froumin 《Applied Physics A: Materials Science & Processing》2012,106(1):181-189
The experiments show that the alloying liquid In with only (0.1–0.5) at% Ti dramatically reduces the equilibrium contact angle
Θ
∞ formed by In on the surface of CaF2. The aim of this paper is to clarify whether this practically important and conceptually challenging effect can be explained
solely by Ti adsorption at the F-terminated solid–liquid interface without resorting to any other Ti-induced effect. The combination
of ab initio calculations and regular solution approximation was proposed for finding the binding energy, ΔE
Ti of Ti adatom with the interface “CaF2/liquid solutions In–Ti.” With thus obtained ΔE
Ti=1.16 eV, we calculated from the Shishkovsky isotherm the reduction in the solid–liquid interface energy, Δγ
SL induced by Ti adsorption from liquid In with various Ti concentration, C. It was found that Δγ
SL(C) dependence demonstrated close inverse correspondence with Θ
∞(C) and that the theory fitted very well all available experimental data on the concentration and temperature dependence of
Δγ
SL. It was concluded that the Ti adsorption effect is large enough to account for the observed wetting improvement. The proposed
multiscale modeling approach to the role of adsorption in wetting can be applied also to other nonreactive systems “liquid
metal–ceramics” where the substrate determines the surface density of the adsorption sites for the active element. 相似文献
16.
Joseph Ben Geloun Vincent Rivasseau 《The European Physical Journal C - Particles and Fields》2008,58(1):115-122
The β-functions of O(N) and U(N) invariant Grosse–Wulkenhaar models are computed at one loop using the matrix basis. In particular, for “parallel interactions”,
the model is proved to be asymptotically free in the UV limit for N>1, and it has a triviality problem or Landau ghost for N<1. The vanishing β-function is recovered solely at N=1. We discuss various possible consequences of these results.
Work supported by the ANR Program “GENOPHY” and by the Daniel Iagolnitzer Foundation, France. 相似文献
17.
The statistical distribution of eigenvalues of pairs of coupled random matrices can be expressed in terms of integral kernels
having a generalized Christoffel–Darboux form constructed from sequences of biorthogonal polynomials. For measures involving
exponentials of a pair of polynomials V
1, V
2 in two different variables, these kernels may be expressed in terms of finite dimensional “windows” spanned by finite subsequences
having length equal to the degree of one or the other of the polynomials V
1, V
2. The vectors formed by such subsequences satisfy “dual pairs” of first order systems of linear differential equations with
polynomial coefficients, having rank equal to one of the degrees of V
1 or V
2 and degree equal to the other. They also satisfy recursion relations connecting the consecutive windows, and deformation
equations, determining how they change under variations in the coefficients of the polynomials V
1 and V
2. Viewed as overdetermined systems of linear difference-differential-deformation equations, these are shown to be compatible,
and hence to admit simultaneous fundamental systems of solutions. The main result is the demonstration of a spectral duality
property; namely, that the spectral curves defined by the characteristic equations of the pair of matrices defining the dual
differential systems are equal upon interchange of eigenvalue and polynomial parameters.
Received: 14 September 2001 / Accepted: 18 February 2002 相似文献
18.
A. Lucchesini S. Gozzini C. Gabbanini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):223-226
By using a spectrometer having as source a commercial etherostructure Al
x
Ga1 − x
As diode laser operating in “free-running mode”, line shape parameters of some water vapor ro-vibrational overtones at 820–830
nm have been measured at room temperature. These weak absorption lines have been detected by using the wavelength modulation
spectroscopy technique with second-harmonic detection. The broadening and shifting coefficients have been obtained by fitting
the collected second-harmonic absorption features while varying the pressure of different foreign gases. 相似文献
19.
P. Darmawan 《Solid State Communications》2006,138(12):571-573
Amorphous Lu2O3 high-k gate dielectrics were grown directly on n-type (100) Si substrates by the pulsed laser deposition (PLD) technique. High-resolution transmission electron microscope (HRTEM) observation illustrated that the Lu2O3 film has amorphous structure and the interface with Si substrate is free from amorphous SiO2. An equivalent oxide thickness (EOT) of 1.1 nm with a leakage current density of 2.6×10−5 A/cm2 at 1 V accumulation bias was obtained for 4.5 nm thick Lu2O3 thin film deposited at room temperature followed by post-deposition anneal (PDA) at 600 °C in oxygen ambient. The effects of PDA process and light illumination were studied by capacitance-voltage (C-V) and current density-voltage (J-V) measurements. It was proposed that the net fixed charge density and leakage current density could be altered significantly depending on the post-annealing conditions and the capability of traps to trap and release charges. 相似文献
20.
G. D. Alkhazov A. E. Barzakh V. P. Denisov V. S. Ivanov I. Y. Chubukov V. N. Fedoseev V. S. Letokhov V. I. Mishin S. K. Sekatsky 《Hyperfine Interactions》1990,61(1-4):1335-1338
New results on spins, electromagnetic moments and isotopic changes of nuclear charge radii for
63
157–159
Eu,
64
146, 148, 150
Cd and
65
147–155, 157, 159
Tb have been obtained from hyperfine structure and isotope shifte measured with laser resonance photoionization technique.
These results complement two-dimensional picture (with respect to H and Z) of the changes of nuclear ground state properties
near the “critical” neutron numbers N=88–90 in the vicinity of the “magric” proten number Z=64. 相似文献