No abstract available

[en] The experimental investigations of electrolysis of gallium in GaCl₃-GaI₃ (50 % mol.) molten salts, penetrating through a three-layer membrane from the quartz cloth (thickness - 1 mm), with the hermetisation of electrolyte by liquid gallium are conducted. The output on the current constituted from 30 to 100 % respectively for three and one-valent gallium. The reached current density was up to 1000 A/mm². The analysis of obtained results is conducted and one a number of suppositions concerning the change of electrolyte properties in the process of tests is made. 4 refs.; 6 figs

No abstract available

No abstract available

[en] The electronic band structures of GaN_xAs_1-x alloys were investigated versus the nitrogen mole fraction x and the nitrogen atomic configuration. The computational method is based on the sp³s* tight-binding technique. Two main nitrogen atomic distributions were considered: (i) the nitrogen atoms grouped in one region to form like a GaN dot inside the GaAs so as to have a maximally N-clustered (MNC) configuration; and (ii) the nitrogen atoms homogeneously distributed over the alloy and, of course, the minimal N-clustered distribution as the maximally As-clustered (MAsC) configuration. The former is found to always have the lowest band gaps. More interestingly, the results show that in the latter distribution the nitrogen atoms introduce resonant states above the conduction-band edge by about 230 meV, which is consistent with the literature, whereas they introduce a deep gap state above the valence-band edge at about 150 meV in the former distribution. As a suitable model for experimental samples, the MAsC configuration, was used to model some available photoluminescence data in the dilute regime

[en] The character of the lowest unoccupied state in the random Ga(As_0.5-yP_0.5-yN_2y) alloys is investigated for small nitrogen concentrations (0.1%<2y<1.0%) using a pseudopotential technique. As nitrogen is added to Ga(As_0.5P_0.5), this state evolves from an impurity localized level to a delocalized bandlike state. This evolution involves two processes. The first process is an anticrossing between the deep-gap nitrogen impurity level existing in the dilute alloy limit y→0 and the Γ_1c-like extended state of Ga(As_0.5P_0.5). The second process is the formation of an impurity subband due to the interaction of the deep-gap nitrogen levels. These two processes are expected to occur in any Ga(As_1-x-y1P_x-y2N_y1+y2) alloys for which x is larger than 0.3

[en] Semi-empirical tight-binding sp³s^* method for tetrahedrally co-ordinated cubic materials is used and applied to study the electronic band structure for GaAs, GaSb and GaP. These compounds are found to be indirect-gap semiconductors under pressure effect. The ionicity factor at critical transition pressure is presented by means of a recent empirical model. The structural phase transition can be seen from the behaviour of the bonding character. The obtained results are in reasonable agreement with experimental and theoretical data

[en] The Moessbauer spectra of ⁶⁷Ga(⁶⁷Zn) and ⁶⁷Cu(⁶⁷Zn) impurity atoms in the bulk of GaP, GaAs, and GaSb samples correspond to isolated zinc centers at Ga sites. The observed shift of the spectral gravity center to higher positive velocities at the transition from p- to n-type samples corresponds to the recharging of a shallow zinc impurity center. Moessbauer spectra of ⁶⁷Cu(⁶⁷Zn) impurities at the surface of samples represent a superposition of spectra corresponding to isolated zinc centers at gallium sites with that corresponding to zinc associates with an arsenic vacancy. (author)

[en] An absolute value was obtained for the isotopic abundance ratio of a reference sample of gallium (Standard Reference Material 994), using thermal-ionization mass spectrometry. Samples of known isotopic composition, prepared from nearly isotopically pure separated gallium isotopes, were used to calibrate the mass spectrometers. The resulting absolute (69)Ga/(71)/Ga ratio is 1.50676 + or - 0.00039, which yields atom percents of (69)Ga=60.1079 + or - 0.0062 and (71)Ga=39.8921 + or - 0.0062. The atomic weight calculated from this isotopic composition is 69.72307 + or - 0.00013. The indicated uncertainties are overall limits of error based on two standard deviations of the mean and allowances for the effects of known sources of possible systematic error

[en] We have investigated the preadsorption of gallium on GaAs(1 1 1)B surface during the self-catalyst growth of GaAs nanowires by first-principles calculations. We found that the Ga adatoms can be stabilized on GaAs(1 1 1)B surface only at low coverage. These Ga adatoms have a tendency to form Ga droplets when the Ga coverage is further increased. The micro-mechanism of Ga droplets formed on GaAs(1 1 1)B surface have also been revealed. The calculated result shows that the Ga adatoms dislike to incorporate on GaAs(1 1 1)B surface. The As adsorption on GaAs(1 1 1)B surface can be promoted by Ga preadsorption. The reason for Ga droplets can be used as collector of As atoms is that the As adatoms can stabilize the Ga preadsorbed GaAs(1 1 1)B surface. Our results are useful to understand the self-catalyst growth of GaAs nanowires