摘要:

Inkjet printing (IJP) technology is a popular technology for desktop publishing. Since some of the conducting (or conjugated) polymers are solution processable, IJP technology becomes an ideal method for printing polymer light-emitting diodes with high resolution. Unfortunately, the polymer film printed from an inkjet printer usually consists of pin-holes, and this intrinsic character makes it unsuitable for fabricating high quality polymer electronic devices, particularly for devices in the sandwich structure. In this letter, we submit a hybrid structure, which consists of an inkjet printed layer in conjunction with another uniform spin coated polymer layer, as an alternative to the regular inkjet printed structure. The uniform layer serves as a buffer layer to seal the pin-holes and the IJP layer is the layer consisting of the desired pattern, for example the red–green–blue dots for a multicolor display. To demonstrate, we applied this hybrid technology to fabricate efficient and large area polymer light-emitting logos. The use of this concept represents a whole new technology of fabricating polymer electronic devices with lateral patterning capability. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121090

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Phosphor thermography, relying on the temperature dependence of the decay time of photoluminescence from suitable phosphors, provides remote measurement of the temperature of components. Such a phosphor is yttrium oxide doped with europium(Y2O3:Eu).Associated with this phosphor is also a rise time. Demonstrated is that the rise time is also temperature dependent, as a result of known electronic transitions within the Eu ions. For the phosphorY2O3:Eu(3.4 at.&percent;), the rise time is an activated process in the temperature region between 25 and 850 °C. Faster than the decay time, the rise time offers the opportunity for measurement of higher velocity components. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121091

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Surface transverse waves (STW) are numerically simulated on langasite. As our method of investigation, we compute the admittance of an infinite synchronous resonator. The resonance and antiresonance frequencies are evaluated as functions of the crystal cut, temperature, and the thickness of the aluminium electrodes. For optimal parameters, we demonstrate a vanishing first-order temperature coefficient at room temperature and find a coupling strength several times stronger than that for Rayleigh waves in ST quartz. In particular, we find that the sensitivity of the resonance frequency to variations in the thickness of the aluminium electrodes is significantly lower in langasite than in ST quartz. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121092

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

An x-ray photoelectron spectroscopy system with a laser-plasma x-ray source is shown to have energy resolution high enough to observe chemical shifts ofSi 2pelectrons inSiO2,Si3N4,and pure Si. A boron nitride (BN) plasma x-ray source is produced by irradiation of 100 mJQ-switched YAG laser pulses. A single line emission at 4.86 nm is selected from the BN plasma by means of carbon foils. Fine spectra are acquired with only 96 laser shots. The results obtained confirm that a laboratory-sized x-ray photoelectron spectroscopy system with submicron spatial resolution and high spectral acquisition speed can be realized. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121093

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In principle, chemical information is obtainable from metal surfaces by means of photon emission from the scanning tunneling microscope (STM). However, the photon emission varies significantly with topography and choice of tip. We address the important issue of geometry by studying the emission characteristics of Ag and Au spheres. First, photon maps of Ag clusters, consisting in some cases of just a few atoms, demonstrate that they can be uniquely identified from other nonmetallic particles. Then, the bias at which there is an onset of photon emission for 1 nm Ag and Au clusters is measured and found to be≈3.3and≈2.1 V,respectively. This allows for the demonstration of the ability of the STM to distinguish different metal particles by their photon emission. The value of the onset bias for each metal can be made almost invariant to sample topography by an appropriate choice of tip; only then is the photon emission related purely to the optical properties of the surface. We envisage a form of chemical microscopy, whereby the bias of emission onset is mapped. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121094

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Long-wavelength optical phonons ofGa1−xAlxNsolid solutions have been identified in a wide compositional range by Raman spectroscopy. TheA1andE1polar phonon frequencies evolve continuously withxfrom one-member crystal to the other. The same behavior seems to hold true for the silentB1mode, which manifests itself by an interference with an unidentified continuum. Coupling of the longitudinal-optic (LO) modes associated with the two types of bonds, via the macroscopic electric field, is treated by a generalization of the dielectric model [D. T. Hon and W. L. Faust, J. Appl. Phys.1, 241 (1973)]. This approach accounts for the observed frequencies and supports the apparent one-mode behavior of the polar LO phonons. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121095

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Studies of accelerated electromigration were conducted on passivated Al single-crystal interconnects fabricated on oxidized Si, and capped withAl3Tioverlayers. The capping layers were formed by the reaction of the single-crystal Al films with Ti overlayers. The activation energy for electromigration-induced failure was determined to be0.94±0.05 eV.Previous work on Al single-crystal interconnects withoutAl3Tioverlayers gave an activation energy of0.98±0.2 eVand lifetimes of similar magnitude [Y.-C. Joo and C. V. Thompson, J. Appl. Phys.81, 6062 (1997)]. The similarity of these results suggests that either the rate-limiting mechanism for electromigration-induced failure of single-crystal Al interconnects is not diffusion along the interface of the Al with the surrounding oxide and overlayer, or that, surprisingly, the diffusivity of Al along theAl/Al3Tiinterface is approximately the same as, or lower than, the diffusivity of Al along theAl/AlOxinterface. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121096

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Here we present the first direct observation of the atomic structure of threading dislocation cores in hexagonal GaN. Using atomic-resolutionZ-contrast imaging, dislocations with edge character are found to exhibit an eight-fold ring core. The central column in the core of a pure edge dislocation has the same configuration as one row of dimers on the {10-10} surface. Following recent theoretical work, it is proposed that edge dislocations do not have deep defect states in the band gap, and do not contribute to cathodoluminescence dislocation contrast. On the other hand, both mixed and pure screw dislocations are found to have a full core, and full screw dislocation cores were calculated to have states in the gap. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121097

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The effects of hydrogen and oxygen plasma treatments on the structural properties ofn-typec-Si were examined. Specimens were exposed to either an oxygen or a hydrogen electron-cyclotron-resonance plasma in a temperature range of 240–385 °C. Hydrogenations performed at low temperatures (<300 °C) introduced platelets. On the other hand, oxygen plasma treatments did not result in the formation of platelets. Analysis of O and H concentration depth profiles, measured by secondary-ion-mass spectrometry (SIMS), reveal that O and H migrate with a similar diffusion coefficient ofDeff≈1012 cm2 s−1.Moreover, the O concentration exceeds the H concentration by roughly a factor of 2.5. This suggests that one H atom and 2–3 O atoms migrate as a cluster. Furthermore, evidence of deep traps for H and O was found from the SIMS depth profiles. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121098

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A novel processing method is developed for preparing sol-gel derivedPb(Zr1−xTix)O3(x=0.47)thin films onPt/Ti/SiO2/Sisubstrates. Using a modified precursor solution and a rapid heat treatment without pyrolysis, it was possible to obtain highly (111) oriented PZT thin films with high perovskite content at a low annealing temperature of 550 °C. The low temperature processing was assisted by taking advantage of the heterogeneous nucleation of the PZT films, which reduces the activation energy for perovskite phase formation. Using this method, the PZT thin films exhibited better dielectric and ferroelectric properties at 550 °C than those reported by other methods. For example, the PZT films annealed at 550 °C showed a well-saturated hysteresis loop at an applied voltage of 5 V withPrandEcof12 &mgr;C/cm2and 38 kV/cm, and their dielectric constant and dissipation factor at a frequency of 100 kHz were 410 and 0.021, respectively. The leakage current density was lower than10−8at an applied electric field of 150 kV/cm. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121099

出版商:AIP    

年代:1998

数据来源: AIP