Volume 11, Issue 1, 01 July 1967
Index of content:
11(1967); http://dx.doi.org/10.1063/1.1754948View Description Hide Description
It is demonstrated that even in the case of weak polar coupling, certain two‐phonon scattering processes lead to rates comparable to one‐phonon scattering. This additional scattering will influence the electron distributions and velocity‐field characteristics calculated for polar semiconductors.
11(1967); http://dx.doi.org/10.1063/1.1754949View Description Hide Description
The transient response of semi‐insulating CdTe to monoenergetic alpha particles is composed of a fast component, characteristic of trapping, and slow component displaying the release of carriers from traps. It is verified that the shape of the fast component is directly proportional to [1 ‐ exp (‐t/τ+)] for electrons where τ+ is the mean free drift time. From an analysis of the shape, τ+ for electrons ranges from 30 to 90 nsec; mobilities from 600 to 1100 cm2/V‐sec. On a single‐level model thermal and optical excitation data indicate a trapping level at 0.6±0.05 eV from the conduction band.
11(1967); http://dx.doi.org/10.1063/1.1754950View Description Hide Description
Diffraction of light at 1.15 μ has been observed from magnetoelastic waves at 1.1 GHz in YIG. A shift in the Bragg diffraction angle was observed when an external magnetic field was varied so as to change the spin wave admixture. The largest shift obtained experimentally was ‐2.0°, measured from the elastic limit of 9.5°. This shift was accompanied by a delay in the diffracted pulse of about 1 μsec. Under quasielastic conditions the diffracted intensity exhibited a series of maxima as the field was swept, due to magnetoelasticFaraday rotation.
11(1967); http://dx.doi.org/10.1063/1.1754951View Description Hide Description
High energy electrons penetrating a solid and emerging from a surface can remove surface atoms by Coulomb interaction with their nuclei. Observations of this desorption process were made on a (100) tungstensurface with an adsorbed layer of thorium atoms of known coverage. Electrons of energy up to 2 MeV were used and the rate of removal of thorium atoms was calculated from the rate of change of work function of a collector surface.Measurements of desorption rate as a function of energy suggest a binding energy of 15 to 20 eV, in contrast to the 8 eV obtained from thermal desorption.
11(1967); http://dx.doi.org/10.1063/1.1754939View Description Hide Description
Thin single‐crystal films of cubic siliconcarbide have been grown on silicon substrates within the temperature range 800‐ 1000°C in high and ultrahigh vacuum by the reaction of unsaturated hydrocarbons, C2H and C2H4 with silicon. The cubic siliconcarbidegrows with a parallel orientation onto silicon, regardless of crystal orientation. The use of ultrahigh vacuum results in high crystal perfection.
11(1967); http://dx.doi.org/10.1063/1.1754940View Description Hide Description
Thin‐film aluminumresistors with thermally grown SiO2 as the substrate have been subjected to very high current densities of the order 0.5 to 2 × 106 A/cm2. The temperature of the resistor is estimated to be (185 ± 15)°C at high current densities. It is observed that an opening occurs in most of these resistors close to the cathode. Experimental evidence is presented to show that electromigration leads to the observed failures in these thin‐film aluminumresistors.
11(1967); http://dx.doi.org/10.1063/1.1754941View Description Hide Description
11(1967); http://dx.doi.org/10.1063/1.1754943View Description Hide Description
Four real images were reconstructed from a coarsely sampled acoustical hologram made with an ordinary microphone. An internal reference was used which electronically simulated two plane reference waves impinging on the acoustical hologram plane at an angle of + and ‐42.55° from the perpendicular. The sound frequency was 20 kHz, with a wavelength of 0.676 in. in air.
11(1967); http://dx.doi.org/10.1063/1.1754944View Description Hide Description
Linear electro‐optic coefficients as large as r ∼ 4 × 10‐5 cm/statvolt have been measured in the system of ferroelectric strontiumbariumniobates, Sr x Ba1‐x Nb2O6. In the first crystals x varies from 0.75 to 0.25, with Curie temperatures ranging from ∼60°C to 250°C. At 15 Mc, the respective half‐wave field distance products range from 48 to 1236 V.
11(1967); http://dx.doi.org/10.1063/1.1754945View Description Hide Description
An analysis of magnetoelastic waves propagating in spatially uniform, time varying magnetic fields is carried out using small signal momentum conservation. The equations of motion are cast in coupled mode form and the usual weak coupling (between positive and negative waves) approximation is made. The magnon/phonon conversion efficiency for propagation in time gradients is then obtained by analogy to the result previously found for the case of spatial gradients. Experiments which support the theory are described briefly.
11(1967); http://dx.doi.org/10.1063/1.1754946View Description Hide Description
The infrared absorption coefficient due to free electrons in a melt‐grown CdSe crystal is measured as a function of the wavelength at 300 and 80°K. Using densities of free electrons and ionized impurities obtained by measurements of Hall effect and conductivity, experimental results on the infrared absorption are compared with the Visvanathan theory which is applicable to the absorption due to electrons in a polar semiconductor.
11(1967); http://dx.doi.org/10.1063/1.1754947View Description Hide Description
A new method is suggested for analyzing the tunneling data from metal‐semiconductor (Schottky)junctions, and the method is appled to p‐type GaAs. The method allows a determination of the argument of the tunneling integral. The results indicate that the tunneling current depends upon the density of states of the semiconductor. This disagrees with Harrison's WKBJ results, but does agree with the recent exact solution of tunneling in Schottkyjunctions.