Si Plate Research Articles

Icems and dcems study of Fe layers evaporated onto Al and Si

Thin layers of57Fe (2.5 nm, 10 nm and 70 nm thickness), vacuum evaporated onto Al and Si plates, have been investigated by conversion electron Mossbauer spectroscopy (CEMS). The measurements were performed employing both a proportional counter and a channeltron for conventional and ultrahigh-vacuum integral CEMS (UHV-ICEMS) studies, respectively, and a channeltron for depth-selective CEMS (DCEMS). The phase analysis of the layers on base of experimental results has indicated the presence of metallic iron and one or two iron compounds, ascribed to iron reaction products formed with the residual gas during evaporation. These products are most likely rather stable iron nitrides, are more or less clustered and are distributed throughout the whole layer.

Au-Si diffusion size effect

Using the dissociative model, diffusion of Au atoms into Si plate has been investigated for temperatures below 1270 K. It is shown that, as the plate thickness decreases, the interstitial regime can change into the vacancy regime of diffusion transfer.

Thermal emission of semiconductors under nonequilibrium conditions

The thermal emission of semiconductors under the fundamental absorption edge at excitation of nonequilibrium charge carriers in them has been investigated. A broad spectrum of various actions upon a semiconductor—photoexcitation, contact injection, magnetoconcentration effect—has been used for the first time for modulation of the emissivity of crystals under isothermal conditions. Spectral, field, temperature and coordinate dependencies of the thermal emission as well as its transient characteristics at a pulsed excitation have been measured. It is shown that a considerable modulation of the thermal emission in a semiconductor can be obtained without a temperature change, through changing its emissivity alone. A number of features of the thermal emission in the region under consideration has been revealed: a spectral maximum which position depends on the optical thickness of the crystal, a kinetics delay effect, etc. It has been established that the thermal emission of an excited semiconductor can be used as a means for determining various parameters of a material. Experiments were carried out on Ge, Si plates and Ge diode structures at 310 ⩽ T ⩽ 350 K.

Bent perfect crystals as neutron reflectors: Test experiments with Si plates

The reflection of neutrons on bent perfect crystals is described theoretically on various scattering conditions. The reflection properties depend on the geometry of the scattering plane with respect to the cylinder axis of the curvature. Some test experiments have been performed and compared with the theoretical predictions.

Infrared absorption studies on the superionic conductor ZrO2− Y2O3 crystal

Infrared absorption spectra of (1− x) ZrO 2− xYO 1.5, which is one of the superionic conductors, have been studied using thin films evaporated on Si plates. From absorption spectra obtained at normal incidence and at oblique incidence it is shown that ZrO 2−Y 2O 3 crystals have well-defined TO and LO infrared active phonons, though they have many defects. From the analysis of the spectra, x-dependences of the force constant and the effective charge are obtained, and it is found that the concept of the virtual ion crystal model is very useful to understand the infrared properties of the superionic conductor ZrO 2− Y 2 O 3 crystal.

Thermodisplacement imaging of silicon membranes

Abstracts 65.70 - 42.60K - 81.70 Recently small-displacement measu- rement technique have made considerableprogress mainly as a result of the multipleapplications in gravitational waves’detec- tion [1], noncontact measurement of surface acoustic waves [2], nondestructive testing [3,4], photoacoustic spectroscospy and mi-croscopy [4,5], etc. A new application ofthis technique in the field of thermodis- placement imaging is presented in this pa-per. Thermoelastic waves excited by means of Joule heating in thin layers were used for visualizing the complex profiles of si-licon membranes used in the fabrication of sensors, actuators and frequency selectiveelements [6]. We used an one-arm phase-op- tical bridge [3] for measuring the thermo-eleastic displacements. The samples (which we worked on) were polished, 250 Rm thick (001)-cut Si plates. Thin membranes of 25 Rm with different geometrical shapes (Fig. Ib) were obtained through selective etch- ing. Narrow 330

CO 2-laser with vibration-proof Q-switch

A CO 2-laser with vibration-proof Q-switching is described. Modulation is achieved by spinning a plane-parallel Ge or Si plate as Fabry-Perot interferometer. A 1.4 mm thick Si interferometer makes it possible to obtain pulses with duration of about 100 ns and a power of 50 kW, which is higher than cw generation by a factor of 2000.

Axial X-ray preionisation of a 10 atmosphere pressure TE CO 2 laser

A short pulse low energy X-ray point source has been used to axially preionise high pressure TE CO 2 laser discharges. Thin Al or Si plates acting as X-ray transmissive windows and IR laser reflective mirrors allow this technique to be easily incorporated into existing discharge units. Uniform discharges at ⩽10 atmospheres operating at relatively low voltages have been achieved, with laser outputs of ∼0.3 J from a 10 cm 3 device.

Radiation damage (blistering) in Al, Cu, Si by exposure to a plasma focus discharge

Plates of Al, Cu (polycrystalline) and Si (monocrystal) have been irradiated with beams of D + ions (keV to MeV) and other radiation by exposure to a single discharge of a 5–10-kJ Plasma Focus in deuterium. Scanning electron microscope and elemental X-ray energy dispersive analysis are used for diagnostics. The nonuniformity of the ion beam causes a nonuniform damage with formation of clusters of blisters. A statistical analysis of blister parameters (diameter and skin thickness) is used to investigate the internal structure of a deuteron beam ejected from the plasma. The value K ∼ 10–20 keV is obtained as the typical ion energy for the bulk of the deuterons and an ion energy E ∼ 200–230 keV is typical for individual ion groups (ion strings) forming the high-energy deuteron beam.

Acoustoelectric effect in piezodielectric semiconductor layered structure

In this paper we report on the observation of acoustoelectric effect (transversal and longitudinal) in the layered structure LiNbO3–Si by means of capacity probes, situated on one side of LiNbO3 thin plate with surface acoustic waves propagating along the opposite side adjacent to the Si plate. These effects arise due to the penetration into the silicon plate of the electric fields of the surface acoustic wave propagating along the LiNbO3 plate. The transversal effect was revealed to be even (i.e., did not change its sign with a reversal of the direction of surface acoustic wave propagation). The longitudinal effect was revealed to be odd. In high-conductivity Si samples (σ≥10−4 Ω−1 cm−1) the transversal effect predominated, in low-conductivity samples the longitudinal effect predominated. Experimental results on the investigation of the transversal acoustoelectric effect as a function of acoustic intensity, conductivity of the silicon specimen, and dc-drift electric field are given. The comparison of these results with the theory of acoustoelectric effect in layered structures is carried out.

Drilling machinability of Al-Si alloys

Drilling machinability test was carried out on Al-Si binary alloys containing 1about 30% of Si. The tool used for the experiments was a drill of the standard type of 5mm in diameter.The time and energy in watt for drilling a predetermined depth was decreased with the increase in Si content; however, there was a maximum at 1013% of Si content.The relation between the drilling time and Si conformed to the fragments of chips. Therefore, the improvement in machinability with increasing Si content would greatly depend upon chip treatments. The machinability was decreased by spherodizing of eutectic Si plate crystals. This tendency was particularly evident in low Si content.In conclusion, it was considered that the drilling machinability was improved by the presence of two phases of proper structres.

Simultaneous reflections and the mosaic spread in a crystal plate

The intensity of an X-ray (Bragg) reflection from a mosaic crystal plate under the conditions of multiple diffractions is discussed theoretically. The set of simultaneous differential equations is solved exactly for the two-beam and the three-beam cases. A second order approximation is given for the multiple beam case, and a third order approximation for the triple beam case. The fact that the ratio R of the peak intensity of a single diffracted beam to the intensity of the same beam under conditions of multiple diffraction depends on the mosaic spread η of the crystal provides a method to obtain this magnitude from the experiment. Preliminary measurements were performed on Si and Ge single-crystal plates under conditions of multiple diffraction. From them experimental values of R were obtained for different planes, which then were used to calculate the mosaic spread of the crystals. In this method only relative intensity measurements have to be used and most of the corrections found to be necessary in other procedures used to determine mosaic spread are not needed. The polarization factor for the case of a double reflection preceded by a monochromator is analyzed and the results are given in an Appendix.

Infrared Filters of Antireflected Si, Ge, InAs, and InSb*

Vacuum-deposited single-, double-, and triple-layer infrared antireflection coatings for Si, Ge, InAs, and InSb have been developed for the 1-μ to 15-μ region. MgF2, didymium fluoride, SiO, ZnS, CeO2, and Si were used for the preparation of the coatings. All of the coatings are hard and durable and can be cleaned and boiled in water for several hours with little or no damage. With these coatings, the transmittance of Si and Ge plates can be increased to a maximum value of nearly 100%, and stays above 90% over a wavelength interval the limits of which are in the ratio of 1.5:1, 2.7:1, and 3:1 for single-, double,- and triple-layer coatings, respectively. InAs and InSb are slightly absorbing, but more than 90% transmittance can be obtained with sufficiently thin antireflected plates. The temperature dependence of absorption in all four of these materials has been measured in the range from 25°C to 250°C.