摘要:

The extended defects induced in silicon by high energy implantation (1.5 MeV B and 2.6 MeV P) have been investigated by plan‐view and cross‐sectional transmission electron microscopy studies and defect etching measurements. The threading dislocations were identified to be long dislocation dipoles generated in the region of the ion projected range which grew up to the surface. The formation of threading dislocations is shown to have a strong dependence on the implantation dose and O concentration. After 900 °C annealing, a high density of threading dislocations was formed for B and P implants in a dose range of 5×1013–2×1014cm−2and 5×1013–3×1014cm−2, respectively. The threading dislocation density in B‐implanted Czochralski Si substrates was found to be much higher than that in B‐implanted epitaxial Si substrates. This difference is attributed to the strong pinning effect of oxygen immobilizing dislocations in Czochralski substrates. Because P impurities are also efficient at pinning dislocation motion in Si, a high density of threading dislocations was observed even in epitaxial Si substrates with P implantation. Two‐step annealing with a first step at 700 °C (to precipitate oxygen) and a second step at 900 °C was found to be very effective at eliminating the formation of threading dislocations. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363103

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Threading dislocations in the silicon layer in three different types of the silicon on insulator samples produced by standard and improved separation by implanted oxygen (SIMOX) processes were investigated by synchrotron x‐ray topography, scanning electron microscopy (SEM), and optical microscopy. The densities and Burgers vectors of the dislocations were first determined nondestructively by synchrotron x‐ray topography. Then the line directions of the same dislocations were determined by SEM after chemical Secco etching. Some of these results were compared with results obtained from optical microscopy of Secco etched samples. The threading dislocations in the Si layer were found to occur mainly in pairs with densities of the order of 105cm−2in standard SIMOX samples and of the order of 104cm−2in improved SIMOX samples. These dislocations have an edge character. Other features of these dislocations, such as the distances between two dislocations forming a pair, orientations of these pairs, and dislocations that change their line direction, are also discussed. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363104

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

To increase the x‐ray optical contrast of Mo/Si multilayers, we study low energy hydrogen ion implantation of amorphous Si layers. Using elastic recoil detection and Rutherford backscattering spectrometry, we measure the result of hydrogen implantation on Si atomic density. We find a lowering of Si atomic density, and, thus, an enhancement of x‐ray optical contrast, as a result of H implantation. We find that the Si atomic density saturates at a minimum of 64±5% of the crystalline value. We have also observed a minor smoothing effect of H+ion bombardment. Combined with Kr+ion bombardment, causing a very much larger smoothing of the Si surface, the atomic density is found to saturate at a minimum of 77±5% of the crystalline value. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363105

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The damage in Fe‐doped InP induced by 1.0 MeV P ion implantation with doses ranging from 5×1013to 2×1015cm−2and effects of rapid thermal annealing (RTA) in the range of 700‐1050 °C were investigated by means of Raman scattering. The shift and asymmetrical broadening of the longitudinal optical phonon peak (LO) and the appearance of a transverse optical mode (TO) show that the Raman scattering is very sensitive to implantation damage. For doses larger than 5×1014cm−2, the TO and LO peaks were markedly broadened, even merged into a single peak, indicating an amorphous structure in the near surface region. Much of the primary damage can be annealed out after RTA at 800 °C for all implantation doses. For RTA below 900 °C, the residual damage decreased with increasing annealing temperature for the low dose case of 1×1014cm−2, but increased for the high dose case of 2×1015cm−2. Only when the annealing temperature is over 900 °C, the residual defects of the high dose case drastically decrease, and nearly full recovery is obtained when the annealing temperature is raised to 1000–1050 °C. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363106

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Si‐implant activation characteristics in AlxGa1−xAs for Al compositions of 0%–70% AlAs are presented for doses of 5.6×1012and 2.8×1013cm−2at 100 keV. For both doses, the effective activation efficiency (&eegr;eff) is relatively constant from 0% to 20% AlAs (&eegr;eff=64% for 5.6×1012cm−2and 37% for 2.8×1013cm−2for 20% AlAs), goes through a minimum at 35% AlAs (&eegr;eff=6.6% for 5.6×1012cm−2and 2.5% for 2.8×1013cm−2), and then increases towards 70% AlAs (&eegr;eff=52.8% for 5.6×1012cm−2and 31.1% for 2.8×1013cm−2). The results are explained based on the compositional dependence of the ionization energy and conduction band density‐of‐states of AlGaAs. The effects of P coimplantation is also studied but demonstrates no significant enhancement of the activation efficiency of Si implantation for 0%–70% AlAs. Finally, data are presented for Se implantation in Al0.2Ga0.8As with a maximum effective activation efficiency of 5.6% achieved. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363556

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In recent x‐ray moire´ topographic experiments a dislocationlike discontinuity of moire´ fringes has been found despite the fact that specimens (Si bicrystal) were dislocation free. This discontinuity, although similar in appearance to the fringe discontinuity known as moire´ dislocation, should be essentially distinguished from it. Preliminary considerations suggest that the outbreak of such pseudo‐moire´ dislocations is related not only to the wave‐field phase due to the moire´ effect, but to the phase of extinction fringes. Pseudo‐moire´ dislocations commonly occur in plane‐wave x‐ray moire´ topography of slightly strained specimens. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363828

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Four aluminum‐jacketed, fluorine‐doped silica clad optical fibers with silica core materials fabricated by differing technologies were subjected to sequential60Co‐&ggr; ray and fission‐reactor irradiations (at ∼20 and 40 °C, respectively), an intervening isothermal anneal (∼20 °C), and a final isochronal anneal (to 600 °C) while monitoring the radiation‐induced absorption spectra in the range ∼400–1000 nm. The two low‐OH/low‐chloride core fibers (one of which was doped with 0.5 mass % fluorine) both developed bands at 660 and 760 nm which exceeded 10 000 dB/km for doses in the range ∼102–106Gy(Si); however, these bands declined to <1000 dB/km by the end of the &ggr;‐irradiation phase [12 MGy(Si) at 5.6 Gy(Si)/s]. All fibers displayed an ‘‘UV band tail,’’ which was the strongest in the high‐chloride core fiber, as well as bands in the range ∼600–630 nm generally attributed to nonbridging‐oxygen hole centers (NBOHCs). During the &ggr;‐irradiation phase the strengths of the NBOHC bands proved to be strongly dependent on the method of core material manufacture. Contrary to previous results for acrylate‐jacketed fibers, no substantial bleaching of the UV‐tail or NBOHC bands took place during &ggr; irradiation despite the continuous propagation of white light powers ∼5–50 &mgr;W. The incremental induced absorption spectra consequent to the reactor‐irradiation [∼4 MGy(Si) &ggr;‐ray dose at 70 Gy(Si)/s, plus a fluence of ≳2.8‐MeV neutrons ∼2×1016cm−2] were much less sensitive to fiber core material. The prospects for developing rad hard optical fibers for fusion reactor diagnostics are discussed in light of these findings.

ISSN:0021-8979    

DOI:10.1063/1.363107

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Metastable body‐centered‐cubic (bcc) Nb–Cr solid solutions were produced by mechanical alloying over a wide concentration range, and investigated by x‐ray diffraction, differential thermal analysis, and transmission electron microscopy. For comparison, metastable bcc and amorphous Nb–Cr alloys were fabricated by sputtering. Upon annealing, the solid solutions prepared by mechanical alloying undergo a transformation to an amorphous phase. The vitrification is polymorphous for a composition Nb45Cr55whereas two‐phase mixtures of amorphous and bcc phases are formed for other concentrations, indicating that metastable equilibria between these two phases develop upon heat treatment. These results, combined with a detailed analysis of the thermodynamic functions of the system, reveal that the amorphous phase has a lower enthalpy and entropy than the bcc phase near equiatomic composition. In consequence, the Gibbs‐energy curves of bcc and liquid/amorphous Nb45Cr55phases versus temperature exhibit two points of intersection, i.e., two melting points, with the amorphous phase being thermodynamically more stable than the bcc phase at low temperatures. Inverse melting is thus thermodynamically possible in the Nb–Cr system, so that the metastable crystalline phase would melt upon cooling. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363048

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Li ions were electrochemically intercalated into sputtered Ti oxyfluoride films. The process was found to be thermally activated with an activation energy depending on the amount of intercalated Li and decreasing with increasing Li content. The chemical diffusion coefficient was thermally activated as well with an activation energy of ∼0.5 eV independent of the amount of intercalated Li. The origin of the activation energy was discussed in terms of the Anderson–Stuart model. It was found likely that strain energy is needed to open up ‘‘doorways’’ in the Ti oxyfluoride structure to allow Li ion transport. The jump length for the Li ions inside the Ti oxyfluoride was estimated to lie in the 4–8 A˚ interval. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363108

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

X‐ray absorption spectroscopy (XAS) was applied to investigate the growth behavior of LaNiO3thin films on Si substrate deposited via radio frequency magnetron sputtering at high temperature. The thickness of deposited film was always proportional to the sputtering time. However, the Ni‐to‐La ratio in the film was found to decrease with increasing substrate temperature. It is due to a loss of Ni on high‐temperature deposition which lowers the film growth rate and leads to a gradual structural change. Nevertheless, the oxidation states of both Ni atom and La atom in the thin films were not influenced by the substrate temperature or sputtering time. All the XAS evidence was consistent with the results from x‐ray reflectivity, x‐ray diffraction, and chemical analysis. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363109

出版商:AIP    

年代:1996

数据来源: AIP