摘要:

Nominally 99.9999% pure silver strips were irradiated near 140°K with 3 MeV electrons. Fluences ranged from 0.05 to 6.7×1018electrons/cm2. In order to observe defects which exist in irradiated specimens by electron microscopy at temperatures below stage III annealing, specimens were thinned, washed, and mounted on a specimen holder below −60°C. They were also dried below −60°C and observed using a liquid‐nitrogen cooling stage. A large number of interstitial loops were observed below stage III. The number of loops was constant but the size of the loops increased with increasing fluence. They shrank and disappeared during stage III annealing. After annealing at 0°C, another kind of small dot defects were observed. The results suggest that the stage III annealing occurs by a vacancy or divacancy migration in electron irradiated pure silver.

ISSN:0021-8979    

DOI:10.1063/1.1658743

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The effect of magnetic field on the reverse characteristics of silicon alloy junction diodes in the breakdown condition has been studied. The breakdown voltage caused by internal field emission has been found to remain unchanged under a magnetic field (maximum field used 15 kOe). On the other hand, the breakdown voltage occuring by avalanche ionization increased by about 15 mV on the application of a magnetic field. In the post‐breakdown region, while the magnetic field caused no change in current in diodes breaking down by the former mechanism, it increased the current (at constant voltage) in diodes having avalanche type of breakdown. Explanations of the observed results have been given.

ISSN:0021-8979    

DOI:10.1063/1.1658744

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The ability of thermoelectric power measurements to permit a description of carrier‐density and phonon‐drag variations caused by photoexcitation was tested in 100‐&OHgr;·cmn‐ andp‐type silicon. At low temperatures the major effect of photexcitation is to decrease the phonon‐drag contribution to the thermoelectric power by increasing the phonon density in the crystal. At higher temperatures the thermoelectric effect can be used to investigate changes in the electronic contribution due to photoexcitation. An apparently anomalous increase in thermoelectric power with photoexcitation was consistently found inp‐type silicon over an intermediate temperature range.

ISSN:0021-8979    

DOI:10.1063/1.1658745

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

We have studied a number of metal alloys in a search for improved ohmic contacts to SiC. A Cu&sngbnd;Ti eutectic alloy wets SiC at 880°C forming a shallow contact which is ohmic onp‐type SiC. An Al&sngbnd;Si eutectic wets SiC at 900° to 1000°C giving a contact which is ohmic onp‐type SiC; the penetration is 300 to 500 Å.

ISSN:0021-8979    

DOI:10.1063/1.1658746

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A theory describing the growth of Gunn domains transverse to their direction of travel is developed. This theory is based on a model in which the dipole moment of a domain causes the field immediately adjacent to its lateral edge to exceed the negative resistance threshold. As the dipole moment begins to build up there, it causes the field farther along the lateral dimension to exceed threshold. From this model the velocity of transverse domain growth can be calculated as a function of the bias field and the maximum domain field. The calculated values of about 108cm·sec−1are in reasonable agreement with available experimental data.

ISSN:0021-8979    

DOI:10.1063/1.1658747

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Schottky‐barrier cold cathodes have been fabricated using Pd onn‐type ZnS. The Pd was deposited in the form of a film 30–50 Å thick on the freshly‐cleaved surface of the ZnS in an ultrahigh‐vacuum system, and cesiation was carried out without removal from the system. Cold emission currents up to 0.01 A/cm2were obtained with an efficiency as high as 1.5%. Barrier height measurements indicate that the electrons enter the junction at an energy level 0.5 eV above the vacuum level, but current characteristics reveal a loss process not yet identified.

ISSN:0021-8979    

DOI:10.1063/1.1658748

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The mechanism of growth of GaP on a cleaved CaF2(111) surface was studiedin situin a high‐energy reflection electron diffraction system. It was found that in the early stages of growth, GaP forms tetrahedral nuclei with {111} faces. The three edges of the tetrahedron are parallel to the three ⟨110⟩ directions. These microcrystals coalesce and form a smooth film after a mean thickness of more than 300 monolayers of GaP is deposited on the surface. Temperatures for epitaxial growth of a single crystal without twinning as a function of the atom arrival rate were studied for GaP on a clean CaF2surface and on a GaP‐covered CaF2surface. It was found that growing GaP without twinning on a bare cleaved CaF2surface requires a temperature ∼65°C higher than on a surface that is covered with GaP. The structural characteristics of the GaP film as a function of the substrate temperature are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.1658749

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Measurement of the intensity of light reflected from SiO2‐coated Si, compared with that reflected from the bare Si substrate, may be used for a SiO2thickness measurement in the range below 1000 Å where conventional methods are difficult to apply. By going into the ultraviolet much improved sensitivity is obtained, and at 200 nm an 18 Å film of SiO2can be detected. Relative reflectance curves for 589, 400, 300, and 200 nm derived from optical theory are presented; thicknesses measured using these curves are in good agreement with those from ellipsometry. The only apparatus required is a commercially available uv‐vis spectrophotometer equipped with a microbeam reflectance attachment operating at near‐normal incidence. Thickness measurement requires a spot 1–2 mm in diameter and is simple, rapid, and nondestructive.

ISSN:0021-8979    

DOI:10.1063/1.1658750

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The structure of a blast wave with ionization at local‐thermodynamic‐equilibrium (LTE) is analyzed by using the method of successive approximation to the non‐similar solution. It is found that ionization has a significant effect on the decaying speed, and the first‐order approximation. Numerical results are presented for plane, cylindrical, and spherical blast waves.

ISSN:0021-8979    

DOI:10.1063/1.1658751

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Results are reported of calculations and measurements of the shock overpressure as a function of distance in an air shock tube driven by an exploding mixture of propane and oxygen.

ISSN:0021-8979    

DOI:10.1063/1.1658752

出版商:AIP    

年代:1970

数据来源: AIP