摘要:

The incorporation properties of implanted or deposited Sb into the Si lattice as a result of irradiation with a pulsed KrF ultraviolet laser have been compared. The surface melting dynamics resulting from laser irradiation have been studied in both cases by time‐resolved optical reflectivity. The distribution profiles of the Sb, deduced from Rutherford backscattering spectrometry and ion channeling measurements, show in both cases a maximum substitutional concentration of 2.1×1021cm−3. Substitutional solubility is limited by interface instabilities which develop during regrowth and lead to the formation of a well‐defined cellular structure, as shown by transmission electron microscopy. For the deposited case, we observe a much larger cellular microstructure in addition to the cells induced by interface instabilities. The large cell structure may result from convection‐induced instabilities.

ISSN:0021-8979    

DOI:10.1063/1.335982

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Rapid thermal annealing of Si after implantation with 60‐keV75As+ions was studied using Raman scattering. Spectra were measured at different stages of annealing. It was found that the as‐implanted amorphous phase was first transformed into the higher‐order amorphous phase before the transformation into the crystalline phase. Regrowth of the crystalline phase occurred only from the substrate side, and no polycrystalline regions could be detected at the intermediate stages of annealing. Electrical activation of the implanted As dopant proceeded simultaneously with crystal regrowth, and complete activation coincided with the disappearance of the amorphous phase. Changes in the Raman spectra of the implanted and annealed crystalline layer caused by the contribution of free electrons were found, allowing the concentration of activated free carriers to be determined.

ISSN:0021-8979    

DOI:10.1063/1.335983

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The rotational viscosity &ggr;1is an essential physical quantity directly related to the response times of liquid crystals. We have developed a new method to determine &ggr;1which utilizes the capacitive detection of the director pattern relaxation in a twisted nematic cell upon switching off the applied voltage of the twisted nematic liquid‐crystal display. Measurements have been performed on two liquid‐crystal mixtures. The agreement between the results obtained with the new method and those obtained from a magnetic field‐induced nematic deformation method is quite satisfactory.

ISSN:0021-8979    

DOI:10.1063/1.335984

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An integral representation of the diffracted intensity from one‐dimensional stepped surfaces and overlayers is obtained based on the single‐scattering (kinematic) theory. We find exact solutions for an arbitrary terrace or island size distribution on stepped surfaces or epitaxial layers in an extremely simple manner. This theory greatly expands the utility of the kinematic analysis of electron, atom, or grazing x‐ray diffraction data. A particularly useful area of application is the quantitative study of the nucleation kinetics during the epitaxial growth of thin films. Several surface ordering models are discussed in terms of this simplified approach.

ISSN:0021-8979    

DOI:10.1063/1.335985

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This paper deals with the propagation of elastic longitudinal waves in a cylindrical hole in an infinite space, the hole being filled with an ideal fluid. The Biot’s problem is treated within the context of the nonlocal elasticity allowing one to extend the Biot solution to the domain of ultrashort waves. A numerical example is solved and illustrated by a graph.

ISSN:0021-8979    

DOI:10.1063/1.335986

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The molecular beam epitaxial growth of GaAs on Si(211) has been investigated. Theoretical considerations had suggested the (211) orientation to be particularly suitable for the nucleation and growth of a zincblende‐type compound semiconductor on a diamond‐type elemental one. The experimental results support the theoretical prediction. Morphologies of thin (≤0.1 &mgr;m) (211) layers are substantially better than for (100) layers, which nucleate poorly and require large layer thicknesses (&bartil;1&mgr;m) to yield good morphologies. When the (211) layer growth is initiated with a thin (GaAs/Al, Ga)As superlattice buffer (0.1 &mgr;m), consisting of 10 periods of 5+5 nm, the (211) morphology rivals that of GaAs(100) homoepitaxial growth. Chemical etching studies as well as transmission electron microscope investigations show the layers to have the (211)Borientation and to be free of antiphase domains, both as predicted. The (211) layers show strong photoluminescence at 4 K. Not intentionally doped layers arentype, with electron concentrations on the order of 2×1016cm−3, except in the immediate vicinity of the Si interface. Some of the conduction parallel to the layer plane appears to take place on the Si side of the interface, where a two‐dimensional electron gas seems to be present. Then‐GaAs/p‐Si heterojunctions themselves show excellent rectification characteristics and photosensitivity. It is concluded that the (211) orientation is almost certainly preferable to the (100) orientation for the growth of GaAs on Si.

ISSN:0021-8979    

DOI:10.1063/1.335987

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Variable temperature Hall‐effect measurements on low‐concentration Si:In samples show the existence of supershallow levels with an activation energy for ionization of about 18 meV. For high concentration Si:In samples, the levels at 18 meV tend to disappear and transform into levels with energy of about 160 meV.

ISSN:0021-8979    

DOI:10.1063/1.335988

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Electron traps in bulkn‐type Hg0.7Cd0.3Te were investigated near the HgCdTe/SiO2interface by use of deep level transient spectroscopy on metal‐insulator‐semiconductor structures [D. V. Lang, J. Appl. Phys.45, 3022 (1974)]. Three electron traps are found with activation energies (relative to the conduction band edge) of 0.12, 0.172, and 0.079 eV, and corresponding capture cross sections of 3.5×10−18, 1.1×10−16, and 1.2×10−18cm2. Depth profiles from the surface to ∼1.0 &mgr;m show the concentration of the 0.172‐eV trap to be uniform while the 0.12‐eV trap shows a strong depth dependence. It is undetectable at the surface, rising in concentration to twice its bulk value at ∼0.5 &mgr;m depth then falling to a value comparable with that of the 0.172‐eV trap in the bulk (1 &mgr;m). Divalent trapping behavior has also been detected. In this case, the deeper state significantly depopulates, enabling a shallower state to then depopulate [J. S. Blakemore,SemiconductorStatistics(Pergamon, London, 1962), p. 156].

ISSN:0021-8979    

DOI:10.1063/1.336304

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Photoluminescence studies have been carried out on liquid‐encapsulated Czochralski GaAs crystals. Two wafers (labeled P1 and P2) originating from the same ingot have been investigated. After close‐contact annealing, the presence of a &bartil;64‐meV deep acceptor was observed in P1‐type samples only. After gallium implantation at increasing doses and annealing, the presence of the &bartil;64‐meV level is also observed in P2‐type samples. Boron implantation at increasing doses also generated the 64‐meV level and, in addition, the &bartil;77‐meV acceptor level, often ascribed to GaAs. Using scaling arguments the 64‐meV level is tentatively ascribed to the first level of a double‐acceptor defect. Owing to the stoichiometric imbalance induced by implantation and annealing and the specific influence of boron implantation, the &bartil;64‐ and &bartil;77‐meV levels are tentatively ascribed to GaAsand BAsantisite defects, respectively.

ISSN:0021-8979    

DOI:10.1063/1.335963

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Infrared wavelength modulation absorption spectroscopy was used in the spectral region of 0.3–1.45 eV and the temperature range of 80–300 K, to study deep level impurities and defects in undoped semi‐insulating GaAs grown by the liquid encapsulated Czochralski technique. The measurements revealed two resonant type peaks with fine structure near 0.37 and 0.40 eV, as well as thresholds and plateaus at higher energies. The sensitivity of the measurements allows us to give credence to changes in the absorption coefficient at levels ∼10−3cm−1. The absorption band at 0.37 eV is interpreted as being due to the intra‐center transition between levels of accidental iron impurity, split by the crystal field. The absorption band near 0.40 eV, can be annealed out by heat treatment, and is considered to belong to a multilevel defect complex. Utilizing the photo‐quenching behavior of the absorption in the spectral region of 0.6–1.4 eV, it was shown that conventional room temperature optical absorption may give erroneous results in measuring the concentration of the EL2 levels, because of appreciable absorption due to other residual deep levels in this spectral region, as revealed by the sensitivity of the wavelength modulation technique.

ISSN:0021-8979    

DOI:10.1063/1.336302

出版商:AIP    

年代:1985

数据来源: AIP