摘要:

The generation and propagation of dislocations in GaAsP‐InGaAs strained‐layer superlattices have been studied using x‐ray topography and electron‐beam‐induced current in the scanning electron microscopy. It is shown that three‐dimensional information about dislocations in the substrate, as well as in subsequently grown epilayers, can be obtained via a one‐to‐one correlation of images obtained from these two techniques. Various types of threading and misfit dislocations are identified and their location specified.

ISSN:0021-8979    

DOI:10.1063/1.341663

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Depth profiles of 60‐ and 100‐keV protons implanted at room temperature to fluences of 1016and 1017H+ions/cm2in Si‐dopedn‐type GaAs have been obtained using ion beam techniques. The profiles of H have been measured as a function of annealing temperature up to 820 K. The redistribution of implanted H is observed to depend on the migration of implantation‐induced defects. The migration of H‐atom‐defect complexes is approximated by an Arrhenius process with an activation energy of 2.16±0.15 eV and a preexponential factor of 2×105cm2/s.

ISSN:0021-8979    

DOI:10.1063/1.341664

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Grain growth has been studied in polycrystalline thin films of Ge, Si, and Au during ion bombardment. The phenomenon has been characterized by varying the ion dose, ion energy, ion flux, ion species, substrate temperature, and thin‐film deposition conditions. Films bombarded with Si+, Ar+, Ge+, Kr+, and Xe+exhibited enhanced grain growth which was weakly temperature dependent and proportional to the energy deposited in elastic collisions at or very near grain boundaries. The effect of these parameters on grain size and microstructure was analyzed both qualitatively and quantitatively using transmission electron microscopy. A transition state model describing the motion of grain boundaries during ion bombardment has been applied to the present experimental data. The results suggest that bombardment‐enhanced grain growth may be due to thermal migration of bombardment‐generated defects across the boundary. The calculated defect yield per incident ion was found to be directly related to enhanced grain growth, and was used to estimate the number of atomic jumps at the grain boundary per defect generated. Grain growth rates during bombardment and thermal annealing were related to their respective point defect populations.

ISSN:0021-8979    

DOI:10.1063/1.341665

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The moving species during ion beam mixing of Si/Ni and Si/Pt bilayers were investigated at temperatures between liquid‐nitrogen temperature (LN2) and 180 °C using imbedded markers and Rutherford backscattering. For Si/Ni samples irradiated with Ar ions, the flux ratio of Si to Ni decreased from 1.6 to 0.2 as the substrate temperature increased from LN2to 180 °C. Over this range of substrate temperatures, the individual amount of Si atoms transported was found to remain unchanged; whereas the transport flux of Ni atoms was observed to increase. Similar temperature dependence of the flux ratio was found for the Si/Pt system. The experimental results indicate that the substantial Si motion is due to the temperature‐independent part of ion mixing which is associated with collision cascades. The Ni motion is characteristic of radiation‐enhanced diffusion which is substrate temperature dependent.

ISSN:0021-8979    

DOI:10.1063/1.342472

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

One precursor to cathode initiated vacuum arc breakdown is the growth of microprotrusions on the surface of the cathode. Ion bombardment activated surface atom transport in the presence of a large applied electric field has been associated with microprotrusion growth. Previous low‐temperature cathode bombardment investigations have been extended into a cathode temperature regime of ∼0.2Tm–0.4Tm, whereTmis the cathode melting point. At cathode temperatures of ∼0.3Tm, helium ion cathode bombardment initiates microprotrusion growth which is epitaxial and confined to particular crystal planes. This form of epitaxial growth is partially associated with the thermally activated component of surface transport present at ∼0.3Tm.

ISSN:0021-8979    

DOI:10.1063/1.341666

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Arsenic implanted into thermally grown SiO2was diffused in ambients of O2and N2, and arsenic distributions in the SiO2were analyzed with secondary ion mass spectrometry (SIMS). Arsenic was implanted at energies between 40 and 70 keV with a dose of 1×1015cm−2and diffused at temperatures between 1000 and 1100 °C. The profiles revealed retarded diffusion in the high‐concentration region (>1×1019cm−3) in both ambients. It was found that for N2annealing the diffusion in the low‐concentration region (<1×1019cm−3) is highly enhanced in the early annealing stage and gradually reduced with annealing time, and that this time‐dependent diffusion depends on the implantation energy and annealing temperature. Arsenic diffusivities and related parameters were extracted by fitting numerically calculated profiles to SIMS data. The time‐dependent diffusion was attributed to the diffusion of interstitial arsenic and its reaction with the SiO2network.

ISSN:0021-8979    

DOI:10.1063/1.341667

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Nucleation of GaAs on Si in molecular‐beam epitaxy is studied by Auger electron spectrometry and reflection high‐energy electron diffraction. It is shown that, if growth is initiated at room temperature and if a GaAs equivalent thickness of ∼15 A˚ is deposited on Si, an amorphous, nonstoichiometric layer is obtained which covers completely the substrate surface. Stoichiometry and monocrystallinity can be restored by thermal annealing at 350 °C by a solid‐phase epitaxy mechanism. Under such conditions the initial stages of GaAs/Si growth can then proceed via two‐dimensional nucleation, instead of the three‐dimensional mode observed at higher growth temperatures.

ISSN:0021-8979    

DOI:10.1063/1.341668

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Anomalously large grains due to secondary grain growth in the ordered Cu3Au thin film were observed by annealing the disordered thin film at 250 °C. No secondary grain growth was observed in the films annealed at 300 and 350 °C. The secondary grains have a preferred orientation of ⟨111⟩. Formation of antiphase domains with sizes larger than the normal grain size was found to accompany the growth of the secondary grains. Transmission electron microscopy showed that the coalescence of ordered grains contributed appreciably to the enlargement of secondary grains and antiphase domains. The driving forces of secondary grain growth and enhanced ordered domain growth are discussed on the basis of surface energy anisotropy and grain boundary migration.

ISSN:0021-8979    

DOI:10.1063/1.341669

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

a‐Si:H films were deposited by direct photochemical vapor deposition using vacuum ultraviolet lights emitted from deuterium (161 nm) and Xe (147 nm) discharge lamps. A source gas of Si2H6was effectively decomposed, and a high deposition rate of 7.5 nm/min could be achieved in the case of the Xe lamp. The films had excellent electrical and photoelectric properties similar to ordinary films deposited by glow discharge, and showed very little degradation of photoconductivity under illumination.

ISSN:0021-8979    

DOI:10.1063/1.342498

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Graphite fibers were intercalated using CdCl2as a Cl source and Cl2as carrier gas. Fibers were synthesized with a resistivity‐density figure of merit comparable to that of copper. These fibers can withstand practical electrical current densities as high as 54 000 A/cm2. Their thermal coefficient of resistivity is 0.0016 °C−1, which is approximately 41% of those for copper and aluminum.

ISSN:0021-8979    

DOI:10.1063/1.341670

出版商:AIP    

年代:1988

数据来源: AIP