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Three-dimensional (3D)-investigations of electrically active interfaces in ZnO varistor materials are performed using electron beam induced current (EBIC) contrast in the scanning electron microscope in combination with the focused ion beam workstation (FIB). Small differences in deep donor concentrations were responsible for the barriers asymmetry under zero applied voltage.

Interdiffusion of Si and Ge, strain relaxation in Si/Si (sub 1-x) Ge(sub x)/Si heterostructures was characterized. This was insignificant when the annealing did not exceed 800 degree Celsius for 90 minutes.

A new study investigates the differences between surface and interfacial molybdenum in the formation of Ti-silicides.

A report is presented on the transmission electron microscopy of quantum dots formed by cycled submonolayer deposition of InAs/GaAs grown on GaAs substrates.

Plastic pre-strain may decrease the yield strength of metallic materials when stressed in the opposite direction, known as Bauschinger's effect, which could considerably influence the performance of the materials. However, various processes on microscopic level associated with the Bauschinger's effect are still not clear. In this study, defect generation, movement and annihilation in single crystal copper during cyclic tension-compression loading processes were simulated using the molecular dynamics method. It was observed that Bauschinger's effect was asymmetrical and the strain hardening was more profound during compression. After plastic compression, the tensile fracture strain was increased. The absorbed energy was self-adjusted during the tension-compression cycles and kept relatively stable during the loading cycles. Efforts were made to understand the mechanisms responsible for these phenomena. [ABSTRACT FROM AUTHOR]

We report an unusual dielectric relaxation phenomenon associated with dipolar defect complexes Ti3+-(Vo2-)• observed in the PbZr0.38Ti0.62O3 multilayers. The dielectric loss aroused by the polarization of defect dipoles varies with time under ac electric fields, and its change can be controlled by an applied dc bias. This abnormally dynamic behavior of dielectric loss can be interpreted by the formation and dissociation of dipolar defect pairs Ti3+-(Vo2-)• by injection of charged carriers. These investigations may be beneficial to getting further insight into the defect dynamics and the mechanism of ferroelectric polarization fatigue and restoration in ferroelectric materials. [ABSTRACT FROM AUTHOR]

In this paper we report the design of high room temperature photoluminescence internal efficiency InGaN-based quantum well structures emitting in the near ultraviolet at 380 nm. To counter the effects of nonradiative recombination the quantum wells were designed to have a large indium fraction, high barriers, and a small quantum well thickness. To minimize the interwell and interbarrier thickness fluctuations we used Al0.2In0.005Ga0.795N barriers, where the inclusion of the small fraction of indium was found to lead to fewer structural defects and a reduction in the layer thickness fluctuations. This approach has led us to achieve, for an In0.08Ga0.92N/Al0.2In0.005Ga0.795N multiple quantum well structure with a well width of 1.5 nm, a photoluminescence internal efficiency of 67% for peak emission at 382 nm at room temperature. [ABSTRACT FROM AUTHOR]

The substitution of barium and strontium for calcium in the pseudo-charge exchange (CE)-type charge ordered manganite Pr0.6Ca0.4MnO3 has been reinvestigated for low substitution levels (<10%). It is shown that Ba or Sr substitution exhibits a greater ability to induce ferromagnetism, metallicity and sharp magnetization, and resistivity multisteps at low temperature (2.5 K) in this phase, than in the CE-type manganite Pr0.5Ca0.5MnO3. The crucial role of the size of the A-site impurity is emphasized, the larger Ba2+ cation being much more efficient than Sr2+ to induce such effects. This study demonstrates that the multistep-like behavior, previously observed for Mn-site substitution in Pr0.6Ca0.4MnO3, can be obtained by A-site substitution, Ba substitution being as efficient as Cr substitution, and Sr substitution having a similar effect to Ga substitution. In the framework of the martensitic mechanism, it is suggested that the introduction of larger cations on the Ca sites, or of non-Jahn–Teller cations on the Mn3+ sites, induces “locally” around them the formation of more symmetric domains within the distorted antiferromagnetic matrix. This structural phase separation would induce the electronic phase separation, favoring the formation of ferromagnetic metallic regions in the antiferromagnetic insulating matrix. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the anomalous positive magnetoresistance (PMR) in Co[sub x]–C[sub 1-x] granular films prepared on Si(100) substrates by pulsed laser deposition method. A much larger positive MR, up to 22% at magnetic field B=1 T and x=2 at. %, is observed at room temperature than at low temperature. Interestingly, the room-temperature response has a B[sup 2/3] dependence when B<1 T and a B[sup 1/2] dependence when B>1 T. Different from the low-temperature PMR, the room-temperature PMR are related with the Si(100) substrates. Furthermore, we show that the intrinsic positive MR at low temperature arise from shrinkage of the wave functions of localized electronic states, while the extrinsic MR effects of the Co[sub x]–C[sub 1-x]/Si structure are obviously determined by another mechanism, which may exist in other similar structures. This in turn has important implications for the optimization of such materials. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effect of ion implantation including ion species (N[sub 2][sup +] and C[sub 3]H[sub 8][sup +]) and the fluences (1×10[sup 14]–5×10[sup 15] ions/cm[sup 2]) on the surface energy of ultrahigh molecular weight polyethylene (UHMWPE) were investigated. The total surface energy increases significantly after implanting with the fluence of 1×10[sup 14] ions/cm[sup 2] regardless of ion species, then, the total surface energy slightly increases for N[sub 2][sup +] implanted UHMWPE and decreases slightly for C[sub 3]H[sub 8][sup +] implanted UHMWPE with a further increase of fluence. The structural changes of UHMWPE with different fluence for different ion species are very similar. The linear chains of UHMWPE are damaged and cross linking is generated after implantation. As the fluence increases, the polymer surface becomes more disordered, and the surface becomes hydrogenated amorphous carbon when the fluence exceeds 1×10[sup 15] ions/cm[sup 2]. The surface roughness increases with the increase of the fluence regardless of ion implantation species. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Propagation and post-acceleration of a pseudospark-sourced electron beam from a three-gap pseudospark discharge chamber were studied in recent experiments. The pseudospark produced an electron beam of two phases, an initial 22 kV, 50 A hollow cathode phase beam of brightness 10[sup 9-10] Am[sup -2] rad[sup -2] followed by a 200 V, 200 A conductive phase (CP) beam of brightness 10[sup 11-12] Am[sup -2] rad[sup -2]. The aim of these experiments was to post accelerate the lower-voltage, higher-current CP beam using an acceleration unit driven by a 40 kV, 125 ns voltage pulse produced by a cable Blumlein. The experiments were realized by attaching an acceleration unit to the downstream side of the anode of the discharge chamber. Both the pseudospark discharge and the cable Blumlein were triggered to ensure time correlation between initiation of the pseudospark discharge and post-acceleration of the beam. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The study is conducted to reinvestigate the multi-step like behavior of magnetization, which was obtained by A-site substitution in Pr(sub 0.6)Ca(sub 0.4)MnO(sub 3) and is similar to the Mn-site substitution in Pr(sub 0.6)Ca(sub 0.4)MnO(sub 3). Barium and strontium substitution have the ability to induce ferromagnetism in manganites and are able to generate ultrasharp steps in magnetization and resistivity.

Presents a study which employed metal vacuum arc ion source to synthesize titanium silicides by titanium implantation directly intro silicon or through a deposited titanium film on silicon wafers. Experimental details; Results and discussion; Conclusion.

Provides information on a study that synthesized refractory metal silicides by using a metal vapor vacuum arc ion source to implant the respective metal ions with high current density silicon and silicon wafers. Methodology of the study; Results and discussion on the study; Conclusion.

Focuses on a study which synthesized iron silicide layers on silicon wafers by iron (Fe) ion implantation technique using metal vapor vacuum arc ion source. Materials and procedure; Description of the formation of Fe silicides; Discussion on the formation mechanism in terms of the beam heating effect.

Investigates the effect of copper, aluminum, silver doping into the platinum spacer layers on the perpendicular anisotropy and magneto-optical Kerr effect of cobalt multilayers. Experimental details; Results and discussion.