摘要:

Siliconp+njunctions irradiated with fast‐neutron fluences (5×1011–5×1013neutrons/cm2) have been experimentally measured using the thermally stimulated current technique. When forward filling voltages are applied, a new peak is found in samples irradiated with fluences greater than 5.6×1011. A cluster model has been developed to describe the new peak and the cluster’s dimensions and defect concentrations have been evaluated.

ISSN:0021-8979    

DOI:10.1063/1.352253

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Ion implantation into metals has the potential of producing metastable compounds and solutions that cannot be achieved using conventional processing methods. However, when high doses of heavy ions into metals are necessitated, the technique is often limited by sputtering effects which dictate a maximum achievable implanted ion concentration in the target. Sputtering of light materials (such as C) by heavy ions is much less significant, however. This study investigates the feasibility of ‘‘protecting’’ a metal target surface from sputtering during a heavy ion implant by using a thin ‘‘sacrificial’’ C layer deposited on the target surface. Uncoated and C‐coated (∼1000‐A˚‐thick C) Cu targets were bombarded with 600–1000 keV I−ions to a total dose of ∼2×1017I/cm2. Uncoated samples displayed typical saturation behavior, retaining between 17% and 42% of the dose, depending on the energy. The maximum I concentration achieved in the uncoated samples was about 6 at. %. Excellent results were achieved with the C‐coated samples, with retentions of 100% and peak I concentrations between 18 and 33 at. %. Significant mixing of C was found to occur at the C/Cu interface, however as the implantation energy was increased the I concentration profile shifted more deeply into the sample and away from the mixed C/Cu region. This suggested that higher energies and careful tailoring of the implant parameters can eliminate any problems with C mixing.  

ISSN:0021-8979    

DOI:10.1063/1.352254

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Amorphous Si0.56G0.44films were deposited on (001)Si by electron beam evaporation in a vacuum having a base pressure of 10−7Torr. They were then wet oxidized at 800 and 900 °C in an open tube furnace for various times. Cross (x)‐sectional and plan view transmission electron microscope techniques were employed to characterize the samples. At 800 °C, 30 min of wet oxidation produced a continuous polycrystalline Si‐Ge layer, whereas 60 min of wet oxidation produced a discontinuous polycrystalline layer. After 100 min of wet oxidation at 800 °C, the Si‐Ge layer was almost completely oxidized and no observable evidence of the epitaxial Si‐Ge layer was found. Wet oxidation at 900 °C for 10 min produced a bilayer structure; one epitaxial and one polycrystalline layer separated by a contamination layer initially present on the substrate prior to deposition. A mostly epitaxial Si‐Ge layer was obtained after 30 min of wet oxidation at 900 °C. These results will be discussed in terms of a previously suggested epitaxial growth model. The failure to obtain an observable epitaxial Si‐Ge layer by wet oxidation at 800 °C will be discussed by consideration of changes in the kinetics and the stability of both SiO2and GeO2at this temperature.

ISSN:0021-8979    

DOI:10.1063/1.352255

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The morphology of oxide precipitates in Czochralski‐grown silicon degenerately doped with boron to the concentration of 1019atoms/cm3was studied after a two‐step anneal using the transmission electron microscope. In addition to square‐shaped precipitate platelets having {100}‐type habit planes commonly observed in lightly doped silicon, it was found that the oxide precipitates in degenerately doped silicon also exhibited a disk‐shaped morphology with both {110}‐ and {111}‐type habit planes. Based upon the result from the calculation of the elastic stress field around the precipitate disk, it is hypothesized that the formation of the disk‐shaped precipitates on the planes other than the {100}‐type planes could be facilitated by localized reduction in the elastic moduli of silicon resulting from degenerately doping with boron. This finding is significant for understanding the fundamental differences in the oxygen precipitation mechanisms between silicon lightly and degenerately doped with boron.

ISSN:0021-8979    

DOI:10.1063/1.352256

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The conditions for operation of two multiplication mechanisms in strained layers are analyzed. These are spiral and Frank–Read type sources. It is shown that a minimum thickness is required for their operation, of the order of four times the critical thickness for the bending over of threading dislocations. The implications for strain relief of mismatched layers are discussed.

ISSN:0021-8979    

DOI:10.1063/1.352257

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The dominant diffusion species in the formation of Al2Cu, Mg2Cu, and Mg2Ni have been determined. These compounds, rich in the lower melting point elements, are the first phases formed in metal/metal binary reactions. It is quite surprising to find that in all three systems, the minority elements, i.e., Cu or Ni, are the dominant diffusing species. This is in marked difference with results obtained in many metal/metal and metal/Si systems, where the dominant diffusion species are usually the majority elements in the initially formed compounds.

ISSN:0021-8979    

DOI:10.1063/1.352258

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Diffusion of an array of molecules in micrometer‐thick films of plasma‐polymerized tetrafluoroethylene has been measured using an optical interferometric technique. The diffusivity is approximately independent of molecular size up to a molar volume of about 100 cm3and drops rapidly for larger molecules. For much larger molecules no penetration of the films is observed. These results suggest that plasma‐polymerized tetrafluoroethylene films are heavily cross linked and that this limits the size of the molecules that can penetrate the polymer. The temperature dependence and the molecular size dependence of the diffusivities are discussed in the context of free‐volume theory.

ISSN:0021-8979    

DOI:10.1063/1.352259

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Antimony &dgr;‐doping layers were made by deposition of Sb on monocrystalline Si, followed by the deposition of amorphous Si and a final solid‐phase‐epitaxy treatment at 620 °C. After post‐annealing at temperatures between 625 and 725 °C, Sb precipitates with a diameter of several nm are observed in the &dgr; plane with the aid of transmission electron microscopy. Using channeling Rutherford Backscattering Spectrometry the increase of the precipitated fraction with time was determined from the minimum‐yield signal. The results are interpreted using a model for the generation of Sb nuclei which grow subsequently due to lateral diffusion of Sb atoms in the &dgr; plane, followed by incorporation into the nucleus. The generation of the nuclei appears to take place by way of two parallel processes: (i) fast, simultaneous generation of a limited number of nuclei at low‐energetic sites in the &dgr; plane, with subsequent diffusion‐controlled growth, and (ii) slow, continuous generation of a larger number of nuclei at random sites in the &dgr; plane, with subsequent incorporation‐controlled growth. The Sb diffusion at the extremely high concentrations under consideration is very fast and concentration dependent, which can be explained by the model of vacancy‐percolation diffusion of Mathiot and Pfister [J. Appl. Phys.66, 970 (1989)]. The activation energy for incorporation of Sb atoms into liquid precipitates appears to be considerably lower than for incorporation into solid ones.

ISSN:0021-8979    

DOI:10.1063/1.352338

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The microstructural degradation of a lattice‐matched Ga0.28In0.72As0.61P0.39/InP heterointerface during Zn diffusion has been investigated using high resolution transmission electron microscopy and Auger electron spectroscopy. The diffusion‐induced intermixing of In and Ga across the GaInAsP/InP interface causes tensile stress in the Ga‐mixed InP side and compressive stress in the In‐mixed GaInAsP side. The effect of the localized interfacial stress on the nucleation of misfit dislocations and on the strain accommodation behaviors thereof are clearly revealed throughout the intermixed region, reaching several thousand angstroms on each side of the interface. The interfacial strain is relaxed by generation of paired dislocations with antiparallel Burgers vectors initiating from the intermixed GaInAsP/GaInP interface. The dislocation morphologies reveal striking contrasts across the intermixed interface: stacking faults in the tensile layer and perfect dislocation tangles in the compressive layer. The dislocation lines are concentrated at the GaInAsP/GaInP interface and along the misfit boundaries in the forefront areas of the intermixed region. A model is proposed to explain the strain relaxation behavior in the intermixed region using the mechanism of homogeneous nucleation and splitting of the paired dislocations from the intermixed interface. Also observed in a limited region on the GaInP side is the precipitation of a Zn3P2phase. The Zn3P2precipitates grow to form epitaxial layers to a certain depth of the intermixed GaxIn1−xP layer, where the Zn3P2crystal lattice coherently matches with the matrix crystal lattice. The precipitation reaction of Zn3P2is explained using the kickout mechanism.

ISSN:0021-8979    

DOI:10.1063/1.352260

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Using alternating exposures of Si2H6and Si2Cl6, very thin Si layers have been grown on the Si(100) surface at temperatures (T) as low as 475 °C. Although this growth method is not truly self‐limiting, some of the desired features for Si atomic layer epitaxy (ALE) are retained, as discussed here. The growth rate of new Si on Si(100) using this method is limited by the thermal desorption of H2and HCl. Doping the surface with boron atoms can lower the growth temperature, due to a weakening of the Si—H and Si—Cl bonds on the surface as observed in the temperature programmed desorption results from H2, HCl, and SiCl2desorption from the clean and the boron‐doped Si(100) surfaces.

ISSN:0021-8979    

DOI:10.1063/1.352261

出版商:AIP    

年代:1992

数据来源: AIP