


卷 44, 编号 7 (2017)
- 年: 2017
- 文章: 7
- URL: https://journals.rcsi.science/1068-3356/issue/view/14108
Article
Orientation-patterned templates GaAs/Ge/GaAs for nonlinear optical devices. I. Molecular beam epitaxy
摘要
GaAs/Ge/GaAs heterostructures in which the GaAs layer lattice on Ge is rotated at a right angle to the substrate plane are grown by molecular-beam epitaxy (MBE). Such heterostructures are grown in different epitaxial setups for GaAs and for Ge with wafer transfer through air tor the first time. It is proposed to use surfactants (Bi, Sb) to control GaAs layer nucleation on Ge.



Effect of sizes of “bowtie” composite nanoantenna elements on above-threshold photoemission spectra
摘要
Strong field effects occurring during the interaction of femtosecond laser pulses with “bowtie” composite nanoantennas are numerically simulated. The effect of the nanoantenna shape and laser pulse parameters on the “plateau” formation in the photoelectron energy spectra is studied. It is shown that the upper boundary of the “plateau” can increase appreciably for the same laser pulse parameters when nanoantenna element sizes are different. Physical explanation of the phenomenon is given.



Effect of degenerate carriers on Si band gap narrowing
摘要
Various mechanisms causing band gap narrowing in strongly heated silicon are considered. In the high-temperature region, it becomes necessary to use Fermi–Dirac quantum statistics to describe carriers, since the silicon chemical potential appears in the valence band and in the conduction band at high carrier concentrations. It is shown that carrier degeneracy under conditions of sufficiently strong heating of intrinsic semiconductor causes strong band gap narrowing. The obtained values of band gap narrowing are compared to experimental results.



Mobile adaptive holographic laser seismometer
摘要
A prototype of a mobile laser seismometer based on a multiturn fiber-optic sensitive element and an adaptive holographic interferometer is developed. The possibility of recording weak seismic waves propagating in the “land-sea” interface region by the laser seismometer is shown. The original multiturn design of the sensitive element of the seismometer provides a threshold sensitivity of 1.6 · 10−7 m/s2 to seismic acceleration. The long-term operation stability of the laser seismometer is provided due to adaptive properties of the interferometer constructed using a dynamic hologram formed in the photorefractive bismuth titanate crystal.



Mobile adaptive holographic laser hydrophone
摘要
A mobile adaptive holographic laser hydrophone based on a dynamic hologram formed in a photorefractive crystal is developed. The hydrophone sensitivity is to –163 dB (rel. 1V/μPa) or 8.6 · 10−3 rad/Pa in the frequency range of 1–15 kHz. Field tests of the hydrophone were performed in water area of a sea bay. The results confirm the efficiency of the use of measuring systems based on adaptive holographic interferometers to solve problems of recording weak signals (acoustic, hydroacoustic, and others) under non-laboratory conditions.



Raman scattering in the submicrometer diamond membrane formed by the lift-off technique
摘要
Spectral characteristics of spontaneous Raman scattering in the submicrometer diamond membrane grown by the hydrogen implantation method are studied in comparison with the single-crystal diamond matrix. A shift in the main line of diamond one-photon excitation (sp3-hybridization) at a frequency of 1324 cm−1 is revealed in the diamond membrane. This fact indicates multiple internal strains (residual compression strains) due to residual defects and is a concequence of the use of the hydrogen implantation method (hydrogen is implanted into diamond to form a sacrificial layer.



Nuclide kinetics involving hafnium and gadolinium nuclei in long–lived isomeric states
摘要
The possibility of accumulating an excess energy in materials–neutron absorbers due to the transition of nuclei to isomeric states during radiative captures of neutrons by stable isotope nuclei with smaller mass is shown. The relation allowing estimation of the parameters of nuclide kinetics, i.e., the processes of neutron capture by nuclei, the formation and decay of isomeric states of nuclei, is derived.


