摘要:

A mathematical model is constructed to interpret the profiles of radioactive Si tracers during silicide formation. This model assumes that only Si moves in the silicide during silicide formation and that the moving Si diffuses in the Si sublattice of the silicide in terms of vacancy mechanism. Analytical solutions of the model for long‐time annealing (i.e., asymptotic profiles) are given. The analytical asymptotic profiles are very accurate for the annealing period generally used in experiments. It is shown that the profiles of the Si tracer in the silicide are almost flat. This thus proves that self‐diffusion of the tracer atoms cannot be neglected as assumed in some published papers. In fact, several experimental tracer profiles are found to be flat in the silicide. Some numerical solutions for short‐time annealing are also given to show how the tracer profile evolves. The result given here can also be used for many intermetallic reactions.

ISSN:0021-8979    

DOI:10.1063/1.335359

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Uniform and epitaxial NiSi2layers were obtained by consecutive irradiation of a Ni thin layer deposited onto Si with Nd‐glass laser irradiation, 30‐ns pulse duration, using up to 15 shots. The best quality epitaxial NiSi2layer, for a 50‐nm‐thick Ni layer deposited on Si(111), was obtained with 10 shots of 1.3 J/cm2energy density. The normalized minimum yield of the Ni signal amounted to 25%. The stability of the formed compound was investigated by furnace annealing in the 300–800 °C temperature range. After annealing at 300 °C‐1 h backscattering and channeling analysis indicated a worsening of the epitaxial quality of the compound. X‐ray diffraction patterns showed the presence of the NiSi silicide in addition to the NiSi2silicide. At 500 °C‐1 h annealing the reaction occurred over long distance and a large amount of NiSi was formed at the expense of the NiSi2and the unreacted Ni. At 800 °C the epitaxial quality of the NiSi2improved and the Ni minimum yield reached 10%. The NiSi2was the only silicide present after irradiation and 800 °C‐1 h annealing. Channeling analysis established also that the NiSi2wasbtype: i.e., the silicide layer was rotated 180° about the surface normal ⟨111⟩ axis of the Si substrate.

ISSN:0021-8979    

DOI:10.1063/1.335360

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Spectroscopic ellipsometry measurements have been used as a probe to provide information on the structure of a hydrogenated amorphous silicon basedn‐itwo‐layer system. Then‐istructure is prepared under the same conditions as ana‐Si:Hp‐i‐ncell with a thin (∼150 A˚)nlayer deposited in a glow discharge from a mixture of SiF4, SiH4, H2, and PH3on top of intrinsica‐Si:H. An effective medium approximation and a linear regression analysis have been used to determine the bulk microstructure of the thick (0.3 &mgr;m)nlayer on quartz as a mixture of volume fractions ofa‐Si (0.74±0.01),c‐Si (0.09±0.02), and void (0.17±0.03). When applied to the thinnlayer in the solar‐cell configuration, however, the corresponding analysis shows evidence of a 100‐A˚ overlayer of very low densitya‐Si, not observed on the thickern‐type material, which dominates the dielectric properties of the thin layer. These results are suggestive of nucleation and growth surface microstructure on the 150‐A˚nlayer and lead to the conclusion that, in the fabrication of high‐performancea‐Si:H based devices using thin layers, such structure must be minimized.

ISSN:0021-8979    

DOI:10.1063/1.335361

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The quality of materials grown by molecular‐beam epitaxy (MBE) is closely related to the surfaces kinetics in which the surface reconstructions, growth temperatures and molecular species play important roles. We present our studies on the MBE growth conditions, surface reconstructions and surface morphologies of A1Sb, GaSb, and InAs grown on (100) GaSb, and of InAsSb and GaInAsSb lattice matched to GaSb using dimers As2and Sb2in a wide temperature range of ∼400–650 °C. Certain surface reconstructions for GaSb and InAs which have not been reported in the literature are identified, and the conditions for their existence are presented.

ISSN:0021-8979    

DOI:10.1063/1.335362

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

GaAs grown on Si substrate with AlP, AlGaP, GaP/GaAs0.5P0.5superlattice, and GaAs0.5P0.5/GaAs superlattice was investigated by varying the structure of the intermediate layers between GaAs and Si by metalorganic chemical vapor deposition. It was found that (1) the insertion of AlP and AlGaP layers makes the crystallinity and the surface morphology better, (2) PL (photoluminescence) intensity with two superlattice layers is about one order of magnitude stronger than that without these layers, (3) the crack formation in the GaAs surface layer can be avoided by the strained superlattice layers, (4) the PL intensity has a maximum at about 20 nm for each layer thickness in the superlattices, and (5) the PL intensity increases and the carrier concentration decreases while increasing the thickness of the surface GaAs and saturates over 3 &mgr;m. The PL intensity of GaAs on Si substrates is about 80% of that grown on GaAs substrates.

ISSN:0021-8979    

DOI:10.1063/1.335363

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We have evaluated the two‐dimensional atomic pair correlation function for surfaces containing finite layers of adsorbed atoms and having a random distribution of steps. The step probabilities for the two lateral directions are mutually dependent. We employ a third‐rank tensor formalism to describe the two‐dimensional array of occupation probability vectors from which we derive the pair correlation function. The two‐dimensional electron diffraction angular profile is obtained from this pair correlation function. We have made detailed calculations with the two‐layer system as an example and found that the diffraction characteristics describe qualitatively a recent molecular beam epitaxy experiment of Si on Si(111) surface.

ISSN:0021-8979    

DOI:10.1063/1.335364

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The influence of deposition pressure on epitaxial crystalline film quality has been investigated with respect to vapor‐phase silicon epitaxial growth (SiH2Cl2‐H2system). It is shown that the crystalline film quality has been improved by reducing the deposition pressure. In addition, a prebaking process at reduced pressure has been found to be effective for obtaining single‐crystalline silicon films with atmospheric pressure deposition as well as reduced pressure deposition. The deposition temperature can be lowered down to 930 °C with perfect crystalline film by reducing the deposition pressure. The crystalline quality of epitaxial films grown at a low temperature of 930 °C using the reduced pressure technique has been verified to be excellent by fabricating bipolar transistors with an oxide isolation technique.

ISSN:0021-8979    

DOI:10.1063/1.335365

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Studies of grain structure, size, distribution, and geometric arrangement are gaining importance especially from the point of view of thin‐film interconnects for micron and submicron semiconductor technologies. We have studied the effect of annealing on the grain growth characteristics of pure Al films. As‐deposited films exhibit a uniform grain size distribution between 500 and 800 A˚. With heat treatment, the average grain size increases with the largest grains exhibiting a parabolic growth with time, limited to a size in the neighborhood of 1 &mgr;. Smaller grains, however, cannot be eliminated and about 30% of the grains are less than 2500 A˚ across. The grain boundaries of the smaller grains have a higher oxygen content than the rest of the film. Lines defined by liftoff exhibit a characteristic grain boundary seam along the length of the line. The implications of the above study in terms of processibility and reliability with respect to electromigration are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.335366

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Thick polycrystalline silicon layers (≥1 mm) were deposited on SiO2‐coated single‐crystalline Si wafers at a wide range of temperatures by vacuum evaporation. The crystalline structure and thermal behavior of the layers were strongly dependent on the deposition temperature. These characteristics were also reflected in the mechanical strength and warpage of the polycrystalline silicon‐coated single‐crystalline Si system. A careful investigation was made to understand the thermal characteristics of the vacuum‐evaporated polycrystalline silicon layers for possible semiconductor device application such as dielectrically isolated integrated circuits.

ISSN:0021-8979    

DOI:10.1063/1.335367

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Composition modulation due to spinodal decomposition in In1−xGaxAsyP1−yquaternary and In1−xGaxAs ternary alloys is observed by transmission electron microscopy in epitaxial layers grown by hydride transport vapor phase epitaxy at 700 °C on (001) InP substrate. A quasi‐periodic fine contrast oriented along [100] and [010] directions is found in all samples over a composition range of 0.20≤x≤0.53 and 0.37≤y≤1. Contrary to the result reported on materials grown by liquid‐phase epitaxy, complete mixing at composition outside the miscibility gap predicted by thermodynamics for bulk crystals is not observed. The evidence indicates a rapid spinodal decomposition by surface diffusion during vapor phase deposition. Furthermore, transmission electron microscopy diffraction contrast experiments on the (110) cross‐sectional view of planar and nonplanar epitaxial layers reveal a columnar structure oriented along the growth direction which is consistent with the surface layer spinodal formation. Additional coarse contrast is observed in InGaAs epilayers. TEM stereo investigation confirms a film thickness variation associated with the coarse contrast.

ISSN:0021-8979    

DOI:10.1063/1.335368

出版商:AIP    

年代:1985

数据来源: AIP