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The flexural strength, elastic moduli, Vickers hardness and fracture toughness for silicate glass-ceramics (anorthite and diopside) containing tricalcium phosphate (TCP) were measured. The microstructures of the silicate glass–ceramics containing TCP were shown to consist of a complex structure of rod-like silicate and TCP crystals. The flexural strengths of glass–ceramics containing 32 wt% TCP for anorthite and 38 wt% TCP for diopside corresponding to a eutectic composition in the phase diagram were 236 and 226 MPa. The Young’s modulus and fracture toughness of the eutectic compositions were 89.4 GPa and 2.5 MPa·m1/2 for anorthite and 126 GPa and 2.3 MPa·m1/2 for diopside, respectively. The anorthite glass–ceramic containing TCP has a lower Young’s modulus in spite of a high strength as compared to other silicate glass–ceramics containing apatite or TCP.

Ultrashallow junctions (∼60 nm) are obtained using low energy BF2 (5 keV) implants in crystalline Si. The variation of junction depth as a function of the dose rate is studied for doses of 1×1014 and 1×1015 cm−2. Boron diffusion is retarded in the tail region for the higher dose rates and consequently the junction depth decreases as compared to the lower dose rates. The residual defect density after a 950 °C, 10 s anneal for a dose of 1×1015 cm−2 is reduced for the higher dose rate as compared to the lower dose rate.

Cobalt silicide layer formation on ultra-shallow junctions (

We have performed an analysis of the structural characteristics of silicon following low-energy (3.5 kV) by plasma source ion implantation from a BF/sub 3/ plasma and postimplant rapid thermal annealing. Cross-sectional high resolution transmission electron microscopy imaging has shown that in the as-implanted silicon the first 5 nm is amorphous; no evidence of dislocations or other extended defects was observed. Rutherford backscattering channeling spectra suggest a similar result. High resolution x-ray diffraction analyses revealed a continuous change in the stress in the implanted layer that ranged from highly compressive in the as-implanted Si to moderately tensile in fully annealed samples. All results show that low energy PSII avoids the formation of extended defects and maintain excellent structural quality following annealing.

It is known that boron transient enhanced diffusion (TED) is influenced by the existence of fluorine. This paper further investigates this phenomenon by separating the damage effect of fluorine from the chemical effect of fluorine. To accomplish this goal, a /sup 20/Ne/sup +/ implant with equivalent energy and dose was selected to simulate the fluorine damage (F has an amu of 19). Three types of samples were investigated. First was a 5 keV BF/sub 2/ implant. The second sample created the same damage profile but the B and F implants were separated using a 1.94 keV 2e15 F/sup +/ followed by 1.2 keV 1e15 B/sup +/ implant. The third sample used a 2 keV 1.8e15 Ne/sup +/ implant to create the amorphous layer followed by a 1.2 keV 1e15 B/sup +/ implant. All three implant sets were then subjected to the same rapid thermal annealing conditions (RTA) between 950/spl deg/C and 1050/spl deg/C for 10 sec in a controlled 300 ppm O/sub 2/ in N/sub 2/ ambient. It was found that F/sup +/ plus B/sup +/ resulted in the least amount of B diffusion with /spl Delta/Xj=20 /spl Aring/ at 950/spl deg/C and 100 /spl Aring/ at 1050/spl deg/C, BF/sub 2//sup +/ and Ne/sup +/ plus B/sup +/ implants showed /spl Delta/Xj>100 /spl Aring/ for all temperatures. Damage behavior was also studied by using transmission electron microscopy (TEM). The defect structure of F+B implant is similar to that of Ne+B implant and different from the BF/sub 2/ implant. Results indicate that the chemical effect of fluorine on boron diffusion dominates over the implant damage effect.

The role of fluorine in suppressing boron diffusion is studied by comparing the diffusion of boron from 5 keV BF/sub 2//sup +/ implants versus 1.1 keV /sup 11/B/sup +/ implants with varying 1.9 keV F/sup +/ implant doses. Prior to B/sup +/, F/sup +/ or BF/sub 2//sup +/ implantation, the surface was amorphized to a depth of 1450 /spl Aring/ using a 70 keV Si/sup +/ 1/spl times/10/sup 15//cm/sup 2/ implant. By implanting the boron, fluorine or BF/sub 2/ into pre-amorphized silicon, the differences in damage are factored out of the experiment. In addition, the pre-amorphizing implant provides a source of silicon interstitials for studying boron transient-enhanced diffusion (TED). Secondary Ion Mass Spectrometry (SIMS) profiles indicate negligible reduction in boron diffusion, even with higher fluorine doses corresponding to F:B ratios>that for BF/sub 2/. Transmission electron microscopy (TEM) analysis shows no effect of the presence of F on the evolution of the source of the interstitials, except at F doses>2/spl times/10/sup 14//cm/sup 2/. Earlier studies also using pre-amorphized substrates, but higher dose B implants, showed a significant effect of F on B TED. By comparing our results on lower dose B to these earlier results on higher dose B, a mechanism for the observed reduction in B TED at high B doses is proposed.

Ultra-shallow junctions are obtained using low energy BF/sub 2/ (5 keV) implants in crystalline Si. The variation in junction depth as a function of dose rate and two-step anneals is studied for doses of 1/spl times/10/sup 14/ and 1/spl times/10/sup 15/ cm/sup -2/. B diffusion is retarded in the tail region for the higher dose rates and consequently the junction depth decreases as compared to the lower dose rates. Junction depth is further reduced for the two-step anneals as compared to the single-step RTA.

Paste-like materials with ability of self-setting are attractive for bone substitutes, since they can be injected from the small hole with minimized invasion to the patient. Although bone cements which set as apatite are clinically used, there is limitation on clinical applications due to their mechanical properties such as high brittleness and low fracture toughness. To overcome this problem, organic-inorganic hybrids based on a flexible polymer are attractive. We have obtained an idea for design of self-setting hybrids using polyion complex fabricated by ionic interaction of anionic and cationic polymers. We aimed at preparation of organic-inorganic hybrids exhibiting self-setting ability and bioactivity. The liquid component was prepared from cationic chitosan aqueous solution. The powder component was prepared by mixing various carrageenans with α-tricalcium phosphate (α-TCP). The obtained cements set within 1 day. Compressive strength showed tendency to increase with increase in α-TCP content in the powder component. The prepared cements formed the apatite in simulated body fluid within 3 days. Novel self-setting materials based on organic-inorganic hybrid can be designed utilizing ionic interaction of polysaccharide.

High implant dose rates and two‐step anneals have been used to optimize ultrashallow junctions (∼60 nm) formed by low‐energy (2–5 keV) BF2 ion implantation. Variation in junction depth and dopant profile as a function of beam current density (dose rate) and damage/activation anneal is studied. Junction depths and transient enhanced boron diffusion, as seen from secondary ion mass spectroscopy, are reduced for increasing implant dose rate. In addition, transmission electron microscopy images indicate that implantation at a higher dose rate yields lower residual defect levels following anneal. Dependence of sheet resistance on dose rate seems to be a function of the amorphizing nature of the implant. At a dose of 1×1014 cm−2, use of a low‐temperature, 600 °C furnace preanneal, prior to a high‐temperature rapid thermal anneal, serves to reduce transient enhanced diffusion. At a dose of 1×1015 cm−2, subtle changes in residual damage are observed while no apparent changes in transient enhanced diffusion or she...

The X-ray diffraction profiles of magnesium, and calcium phosphate glasses have been measured and the pair function distributions (PFDs) were calculated. Using the pair function method, distance and coordination numbers for the pairs of PO, OO, and MO (M = Mg, Zn or Ca) were determined. A fundamental unit of the structure in these phosphate glasses is confirmed to be a PO4 tetrahedron. It is found that in the calcium phosphate glass the PO4 tetrahedra from long chains and almost all Ca2+ are surrounded by 6 oxygens, which agrees with the structural model by other workers. In contrast to this normal-type calcium phosphate glass, it is also realized that the structures of the abnormal-type magnesium and zinc phosphate glasses consist of long chains with many branches, and most of Mg2+ and Zn2+ are surrounded by 4 oxygens. Thus, the distinct structural difference for abnormal-type phosphate glasses was recognized by the present X-ray diffraction results. However, an abrupt change of an oxygen coordination number around a metallic ion at the metaphosphate concentration was not observed, which is previously considered to be a main reason for the abnormal behavior in the abnormal-type phosphate glasses.

An X-ray diffraction study has been carried out on binary phosphate and silicate glasses with MgO or CaO in equimolar composition. The structure of a 60 mol% CaO–40 mol% Al2O3 glass was also investigated for comparison. The electron radial distribution function was calculated by the usual Fourier transformation and interpretation of it was made in terms of pair functions. The number of oxygens around magnesium is evaluated to be four in both phosphate and silicate glasses. On the other hand, the number of oxygens which surround calcium appears to depend upon the component of network formers: namely, the oxygen coordination numbers around calcium are five in phosphate, six in silicate and four in aluminate glasses, respectively.