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The photoluminescence (PL) behavior of pulsed laser deposition (PLD)-deposited Si-based nanoporous SiO(sub x)/Si, SiN(sub x), and SiO(sub x) thin films, having completely different chemistries and microstructures is investigated. The results demonstrate that the red PL peak at 1.5 eV is due to the localized states at the oxidized surfaces of these materials, while the green PL peak at 2.3 eV is due to oxygen-related defects in their local disordered nanostructures.

In this article, molecular dynamics simulation was performed to study the heat transport in secondary particles chain of silica aerogel. The two adjacent particles as the basic heat transport unit were modelled to characterize the heat transfer through the calculation of thermal resistance and vibrational density of states (VDOS). The total thermal resistance of two contact particles was predicted by non-equilibrium molecular dynamics simulations (NEMD). The defects were formed by deleting atoms in the system randomly first and performing heating and quenching process afterwards to achieve the DLCA (diffusive limited cluster-cluster aggregation) process. This kind of treatment showed a very reasonable prediction of thermal conductivity for the silica aerogels compared with the experimental values. The heat transport was great suppressed as the contact length increased or defect concentration increased. The constrain effect of heat transport was much significant when contact length fraction was in the small range (<0.5) or the defect concentration is in the high range (>0.5). Also, as the contact length increased, the role of joint thermal resistance played in the constraint of heat transport was increasing. However, the defect concentration did not affect the share of joint thermal resistance as the contact length did. VDOS of the system was calculated by numerical method to characterize the heat transport from atomic vibration view. The smaller contact length and greater defect concentration primarily affected the longitudinal acoustic modes, which ultimately influenced the heat transport between the adjacent particles. [ABSTRACT FROM AUTHOR]

Breathing oscillations in the discharge of an enlarged cylindrical-anode-layer Hall plasma accelerator are investigated by three-dimensional particle-in-cell (PIC) simulation. Different from the traditional breathing mode in a circular Hall plasma accelerator, the bulk plasma oscillation here is trigged by the potential barrier generated by the concentrated ion beam and substantial enough to compete with the anode voltage. The electric field near the anode is suppressed by the potential barrier thereby decreasing the electron density by ∼36%. The discharge is restored to the normal level after the concentrated beam explodes and then it completes one cycle of electro-driven breathing oscillation. The breathing mode identified by the PIC simulation has a frequency range of ∼156 kHz-∼250 kHz and does not vary monotonically with the discharge voltage. [ABSTRACT FROM AUTHOR]

Using first-principles method within the framework of the density functional theory, we study the formation energies and the binding energies of multiple hydrogen-mercury vacancy complex impurities (nH-VHg, n = 1,2,3,4) in Hg0.75Cd0.25Te. We find that, when mercury vacancies exist in Hg0.75Cd0.25Te, the formation of the complex impurity between H and VHg (1H-VHg) is easy and its binding energy is up to 0.56 eV. In this case, the deep acceptor level of mercury vacancy is passivated. As the hydrogen concentration increases, we find that the complex impurity between VHg and two hydrogen atoms (2H-VHg) is more stable than 1H-VHg. This complex passivates both the two acceptor levels introduced by mercury vacancy and neutralizes the p-type dopant characteristics of VHg in Hg0.75Cd0.25Te. Moreover, we find that the complex impurities formed by one VHg and three or four H atoms (3H-VHg, 4H-VHg) are still stable in Hg0.75Cd0.25Te, changing the VHg doped p-type Hg0.75Cd0.25Te to n-type material. [ABSTRACT FROM AUTHOR]

A 4 nm layer of ZrO[sub x] (targeted x∼2) was deposited on an interracial layer (IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 300°C. Some as-deposited layers were subjected to a postdeposition, rapid thermal annealing at 700°C for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous ZrO[sub 2]-rich Zr silicate containing about 15% by volume of embedded ZrO[sub 2] nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-ZrO[sub 2] (t-ZrO[sub 2]) and monoclinic-ZrO[sub 2] (m-ZrO[sub 2]) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interracial layer (IL) was partitioned into an upper SiO[sub 2]-rich Zr silicate and the lower SiO[sub x]. The latter was substoichiometric and the average oxidation state increased from Si[sup 0.86+] in SiO[sub 0.43] (as-deposited) to Si[sup 1.32+] in SiO[sub 0.66] (annealed). This high oxygen deficiency in SiO[sub x] was indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor (MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of ZrO[sub 2] and SiO[sub 2], and the capacitance in accumulation (and therefore, EOT and k[sub Zr-O]) was frequency dispersive, trends well documented in... [ABSTRACT FROM AUTHOR]

The omega head, an experimental thin film inductive head with 120 turns, consists of 6 micrometer pitch helical coils. It also contains an omega- shaped yoke structure which has two axes. The yoke is enclosed by hardbacked photoresist insulator layers which provide smooth wafer surface features.

The back-hopping is observed in current directions corresponding to parallel-to-antiparallel and antiparallel-to-parallel switchings. The threshold voltage for back-hopping has decreased together with spin-torque switching and junction breakdown thresholds and the increase in the anisotropy field by increasing the MTJ aspect ratio has raised the threshold voltage of back-hopping.

The breakdown distribution of a magnetic tunnel junction (MTJ) with an ultrathin MgO barrier is analyzed and two distinct distributions are identified. The breakdown distribution with high value has shown a wide peak-to-peak separation to the critical spin torque induced switching voltage and the low breakdown percentage is reduced by increasing the RA value and MTJ process optimization.

Energy contamination during decelerated ion implantation can affect the post annealing diffusion of B implants adversely. Highly monochromatic beams are required to satisfy device requirements.

Provides information on a study that generated nonsynchronous change of temperature rise and thermal expansion in thin films using transient laser pulse. Experimental procedures; Results and discussion on the study; Conclusion.

Focuses on the alloy semiconductor Hg1-x Cdx Te for the fabrication of high performance photoconductive detectors in the 3-5 and 8-14 mu m spectral ranges. Computation of subband dispersion relations as a function of the surface electron concentration in the accumulation layers of n-Hg1-x Cdx Te photoconductive detectors; Application of the quantitative mobility spectrum analysis.

Deals with a study which analyzed free-carrier absorption of Hg[sub1-x]Cd[subx]Te epitaxial films. Theoretical procedure; Results and discussion; Conclusion.

Focuses on a study which obtained the intrinsic absorption spectra for very thin Hg[sub 1--x]Cd[sub x]Te bulk samples with compositions x at different temperatures. Discussion on the measurement for the intrinsic absorption spectra and KK relation; Analysis of refractive index dispersion; Conclusion.

Focuses on a study which investigated the effect of multiband electron-hole scattering on steady-state minority-electron transport in room-temperature gallium arsenide, using the Monte Carlo method. Details of electron-hole scattering processes; Methodology of the study; Results and discussion.

The switching behaviors in elliptic shaped (aspect ratio=2) submicron magnetic tunnel junctions using CoFeB single free layer and CoFeB/Ru/CoFeB synthetic antiferromagnetic (SAF) free layers are studied. It is found that under considerable stray fields originating from pinned layers, junctions with single free layer show complex switching behaviors with larger Hc variations. In contrast, junctions with SAF free layers exhibit kink-free R-H loops and less Hc variations. The Hc of junctions with SAF free layers is less dependent on the junction size than that with a single free layer. Furthermore, for junctions smaller than a critical size the SAF free layers have a smaller Hc than single free layers. [ABSTRACT FROM AUTHOR]

We have shown that energy contamination introduced by deceleration technology, for increasing the beam currents available for low energy boron implants, can affect fabricated junctions adversely. Energy contamination at a level of 0.1% can extend the profile of 0.5 keV B implants 10 nm deeper after a 1050 °C spike annealing. A highly monoenergetic beam with energy contamination less than 0.1% is required for submicron devices. Furthermore, we have used MeV implantation as a technique of point defect engineering (PDE) to control boron diffusion. PDE can reduce boron clustering and enhance boron activation. Diffusion of B in the tail region has been reduced significantly and the boron profile is much sharper. PDE lowers the critical requirement for beam purity. We conclude that shallower and sharper box-like boron junctions can be achieved by PDE with sub-keV B implants with highly monoenergetic beams. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which developed a surface potential model for the subband structures in the inversion layer of narrow-gap semiconductor heterostructures. Review of related literature; Computational approach; Results.

Presents a study which focused on an experimental model for evaluating the hole subband structures in the p-type channel of semiconductor heterostructures. Measurement of the hole subband structure; Relevant parameters obtained for the hole subband; Conclusion.

The optical constants of highly (100)-oriented LaNiO[sub 3] thin films on Pt(111)-Ti–SiO[sub 2]–Si substrate derived by metalorganic deposition have been obtained using spectroscopic ellipsometry techniques in the wide wavelength range from ultraviolet to far infrared. In fitting the dielectric functions of LaNiO[sub 3], two harmonic oscillators are observed, one is believed to come from the valence–conduction interband transition and the other is attributed to the transition from a donor band to the conduction. Simultaneously the frequency of plasmon is also obtained, which results from the strong electron–electron interaction. Based on these optical and electrical properties, a promising application of LaNiO[sub 3] thin films in infrared microsensors has been proposed. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]