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The reduction of transient enhanced diffusion (TED) with reduced implantation energy has been investigated and quantified. A fixed dose of 1×1014 cm−2 Si+ was implanted at energies ranging from 0.5 to 20 keV into boron doping superlattices and enhanced diffusion of the buried boron marker layers was measured for anneals at 810, 950, and 1050 °C. A linearly decreasing dependence of diffusivity enhancement on decreasing Si+ ion range is observed at all temperatures, extrapolating to ∼1 for 0 keV. This is consistent with our expectation that at zero implantation energy there would be no excess interstitials from the implantation and hence no TED. Monte Carlo modeling and continuum simulations are used to fit the experimental data. The results are consistent with a surface recombination length for interstitials of

Extended defects from 5-, 2-, and 1-keV Si+ ion implantation are investigated by transmission electron microscopy using implantation doses of 1 and 3×1014 cm−2 and annealing temperatures from 750 to 900 °C. Despite the proximity of the surface, {311}-type defects are observed even for 1 keV. Samples with a peak concentration of excess interstitials exceeding ∼1% of the atomic density also contain some {311} defects which are corrugated across their width. These so-called zig-zag {311} defects are more stable than the ordinary {311} defects, having a dissolution rate at 750 °C which is ten times smaller. Due to their enhanced stability, the zig-zag {311} defects grow to lengths that are many times longer than their distance from the surface. It is proposed that zig-zag {311} defects form during the early stages of annealing by coalescence the high volume density of {311} defects confined within a very narrow implanted layer. These findings indicate that defect formation and dissolution will continue to con...

The effect of in situ photoexcitation during boron ion implantation on subsequent transient enhanced B diffusion in Si has been investigated. Photoexcitation using a mercury arc lamp was performed during B+ implantation at 35 keV for a dose of 5×1014 cm−2 at 177 K. A reduction in the electrical activation dip, i.e., reverse annealing effect, in the temperature range 550–700 °C was observed. Also, the transient enhanced diffusion of B, measured using SIMS following 800 °C, 30 min annealing, was suppressed. Both effects demonstrate that the creation of self‐interstitials during the implantation process is significantly reduced.

We propose a method to dope silicon with phosphorus by means of the nuclear resonant reaction 30Si(p,γ)31P, which takes place when a natural silicon target is bombarded with a few MeV proton beam. This alternative method considerably reduces the usual target damage produced by the more commonly used direct phosphorus implantation. Partial support from the Spanish DGICYT (Project Nos. PB92-0341 and PB93-1125). N.P.K. thanks the Spanish DGICYT for financial support (SAB93-0182) during his sabbatical stay in the Universidad de Murcia.

The influence of in situ perturbations of the silicon target crystal electronic subsystem during H+ ion implantation has been studied in terms of the type, density, and spatial distribution of accumulated deep traps. A perturbation of the electronic subsystem was achieved through application of a reverse bias to diode test structures. A substantial decrease in deep trap concentration is observed when ion implantation is accompanied by a superimposed reverse bias. The effect is especially pronounced for hydrogen related deep traps at Ec−0.3.

The localized formation of continuous silicide layers via solid state reaction of nickel atoms with ion implantation preamorphized silicon is described. Ni films 12 nm thick were evaporated on 65 nm deep amorphized surface layers. The silicidation reaction was induced by two stage thermal annealing at 360 and 400 °C, well below the solid phase epitaxial regrowth temperature for amorphous Si and the normal NiSi2 formation temperature. Rutherford backscattering with channeling, XTEM, and four‐point‐probe measurements were used to determine the structure, interfacial morphology, composition, and resistivity of the silicide films. After the lower temperature annealing stage a continuous layer of NiSi2 is formed with an underlying residual amorphous region located above the crystalline substrate. During a second annealing the residual amorphous areas recrystallize epitaxially with respect to the substrate via lateral silicide growth. The process leads to formation of a continuous 35 nm thick nickel disilicide layer completely confined within the original amorphous region. Silicide resistivity was 44 μΩ cm. The process may be viewed as a low‐temperature process enhancement to self‐aligned silicide (SALICIDE) technology since silicide growth proceeds only on preamorphized areas of the silicon substrate.

In this letter we examine the interdiffusion and reaction of deposited cobalt layers during the formation of nanoscale (

The possibility of high-density information encoding in magnetic materials by topologically stable inhomogeneous magnetization configurations such as domain walls, skyrmions, and vortices has motivated intense research into mechanisms enabling their control and detection. While the uniform magnetization states can be efficiently controlled by electric current using magnetic multilayer structures, this approach has proven much more difficult to implement for inhomogeneous states. Here, we report direct observation of fast reversal of magnetic vortex by electric current in a simple planar structure based on a bilayer of spin Hall material Pt with a single microscopic ferromagnetic disk contacted by asymmetric electrodes. The reversal is enabled by a combination of the chiral Oersted field and spin current generated by the nonuniform current distribution in Pt. Our results provide a route for the efficient control of inhomogeneous magnetization configurations by electric current.

Delta‐doping layers in silicon have been made by deposition of 0.39 monolayer Ga on Si(001). The dopant atoms have been buried in the host crystal using a solid phase epitaxial growth method. The grown structures are characterized in situ by high‐resolution Rutherford backscattering spectrometry. A fraction of 30% of the Ga atoms is located at subsitutional sites in a spike less than 1.0 nm wide; the other atoms are at the surface. The surface atoms desorb upon annealing at 985 K, whereas the buried atoms are redistributed only slightly. At temperatures higher than 1100 K the profile degrades completely.

The spectrum of the stimulated Brillouin—compressed subnanosecond laser radiation is studied experimentally in a wide range of pump intensities up to the eightfold threshold value. It is found that at intensities increasing four times the threshold, the spectrum splits and acquires a two-humped shape, which is explained by the phase modulation near the Brillouin resonance. Analytical model of self-phase modulation in stimulated Brillouin compression is developed, which describes the observed spectral splitting and formation of the frequency chirp.