Passivation of the GaP(111) surface by treatment in selenium vapors

Results of examination of structural phase transitions on the GaP(111) surface after heat treatment in selenium vapors in a vacuum chamber with a quasi-closed volume are described. The electrophysical characteristics of Schottky-barrier diodes on GaP(111) are studied before and after treatment in selenium vapors by measuring the current-voltage characteristics and by deep-level transient spectroscopy. It is found that, after treatment in selenium vapors, the Schottky-barrier height becomes dependent on the work function of the metal in accordance with the Schottky-Mott rule for an ideal diode. It is shown that a decrease in the density of surface electronic states in GaP(111) results from the formation of a Ga₂Se₃(111)(√3 × √3)-R30° surface phase with ordered stoichiometric gallium vacancies.     

Innovative technologies for full utilization of ash generated at coal-fired thermal power stations for producing alumina and construction materials

The possibility of full 100% usage of ash from coal-fired thermal power stations for producing raw materials for the cement and alumina industries is considered, and it is shown that comprehensive processing of ash from coal-fired thermal power stations is required for this purpose.     

Increasing the resolution in images of two mutually coherent sources

It is shown that the use of the spatial phase shifting method for determining the distance between two mutually coherent point sources serves to improve resolution more than ten-fold. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 19–21, March, 2008.     

The Influence of Solvent Vapors on the Rheological Properties and Permeability of Butadiene–Styrene Films Studied by Quartz Acoustic Gravimetry

Rheological properties and diffusion permeability of butadiene–styrene film in vapors of organic solvents were studied in both the equilibrium and nonequilibrium states. The investigations by quartz acoustic gravimetry showed that, under the influence of butadiene, acetone, ethanol, dimethylformamide and water vapors, the shear modulus and mechanical losses of the film decreased. This effect was inversely proportional to distance R_a between the centers of the Hansen solubility spheres of a polymer and solvent. The extent of this decrease for R_a = 13 MPa^0.5 is significantly higher than that within a range of R_a ≥ 13 MPa^0.5. The dependences describing the changes in the shear modulus coincided qualitatively with that for the swelling degrees versus distance R_a. Under the influence of vapors, the kinetics of frequency changes in a “resonator–film” system can be described by two exponents: the first short exponent characterizes the permeability of a polymer film before the exposure in vapors and during the first minutes of the process, and the second one is one to two orders slower and covers a subsequent period. The time constant of the short exponent is proportional to R_a.