Cells ofRhodotorula gracilis form under certain conditions equatorial rings, visible in the UV-fluorescence microscope after staining with a CFW brightener. The ultrastructural studies showed that the above rings are formed by a centripetal thickening of the cell wall. Mitochondria with circular cristae and anomalous, ring-like mitochondria were observed in cytoplasm of the cells with developed rings.

A phenomenological theory of the Hall effect in polycrystalline semiconductors is elaborated which makes it possible to interpret reasonably the experimental results obtained from Hall effect measurements. The theory is based on the analysis of the Hall effect in the individual grains and intergrain domains forming the polycrystalline semiconductor. Explicit calculations of the expressions for the Hall constant, Hall scattering coefficient and Hall and conductivity mobilities are performed for wide-gap n-type semiconductors. It is shown that the models of Volger and of Berger are special limiting cases of the theory presented and that the model of Petritz can be extended to the problems of the Hall constant and the Hall mobility in a simple way.

A phenomenological model for the electrical conductivity in polycrystalline semiconductors is presented, using the assumption that an isotype heterojunction with a certain interface state density exists at the grain-intergrain domain interface. Tunnelling, thermionic emission of carriers through the intergrain barriers and ohmic conductivity of the heterojunction are all considered as possible charge transfer mechanisms. Explicit calculations are performed for wide-gap n-type semiconductors and a general expression is derived for the electrical conductivity. It is shown that the known models of Petritz and van den Broek, and also the expression for the conductivity of monocrystalline semiconductors, are special limiting cases of the theory presented.

The new antifungal antibiotic mucidin induces morphological changes in the test microorganism Candida pseudotropicalis. The antibiotic influences shape and size of the cells. Changes in membrane structures, particularly in mitochondria, were observed.

The diffusion potentials in heterojunctions as function of the bulk parameters of semiconductors used and of the density and energy position of interface states are determined. The calculation is made for acceptor- and donor-like states, further the semiinfinite and finite geometries of semiconductors forming the heterojunction are considered. The numerical solution for some interesting cases is shown. [Russian Text Ignored.]

The determination of the electronic properties of the inaccessible surface of a semiconductor thin film using the MIS capacitance method is described. The method is based on the fact that the space-charge capacitance at the accessible surface depends on the properties of the space-charge region of this surface and on the electronic properties of the inaccessible surface. The method was verified by studying the CdSeSixOy interface. A difference of10–15% between results obtained using the present method and results of a direct measurement was found.

The interface properties and transport parameters of CdSeSixOy and CdSeDy2O3 thin film structures in “gap” configuration have been studied. The deposited SixOy changed the depletion layer originally present at the CdSe surface into an accumulation one while the deposited Dy2O3 only lowered the depletion of the CdSe surface. The creation of an accumulation layer at the CdSeSixOy structure results in a greater influence of the CdSe surface on the carrier scattering in the CdSe film. An attempt was made to explain the different behaviour of the dielectrics used. Es wurden die Grenzschichteigenschaften und Transportparameter von CdSeSixOy-und CdSeDy2O3-Dünnschichtstrukturen in Spaltzellenanordnung untersucht. Durch aufgedampftes SixOy wird die an der CdSe-Oberfläche ursprünglich vorhandene Verarmungsrandschicht in eine Anreicherungsrandschicht umgewandelt, während durch aufgedampftes Dy2O3 die Randverarmung lediglich erniedrigt wird. Die Erzeugung einer Anreicherungsschicht an der CdSeSixOy-Grenzschicht hat einen größeren Einfluß der CdSe-Oberfläche auf den Streuprozeß in der CdSe-Schicht zur Folge. Es wurde versucht, das unterschiedliche Verhalten der verwendeten Dielektrika zu erklären.

The influence of annealing of low-resistance polycrystalline thin CdSe films in selenium vapour on the basic transport parameters was studied and an attempt was made to explain the mechanism involved in the electrical conduction of such films. The dependence of the effective mobility, carrier concentration and the conductivity of the annealed films shows that the film resistivity increase during the annealing process is caused predominantly by the carrier concentration decrease in the grains. From the 1/T dependence of the effective mobility and carrier concentration it follows that the intergrain barrier height changes and in consequence the carrier concentration in the intergrain domains also changes. From the same dependence it can be seen that the unannealed films are degenerate. The temperature dependence of the effective mobility shows that the predominant scattering mechanism in the unannealed films is impurity scattering. This is progressively dominated during the annealing (in selenium vapour) by grain boundary scattering, space charge region scattering in the grains and film surface scattering. Further evidence of this was provided by the measured field-effect dependence of the effective mobility.

The influence of substrate temperature in the range 25°–200°C on the basic electrical properties of CdSe thin films has been studied and a comparison with the results of other authors and with the electrical properties of CdSe thin films annealed in oxygen and selenium vapours has been made. It is shown that in the temperature range in which the grain size of the film does not change with the substrate temperature, the film resistivity increases with increasing substrate temperature while the carrier concentration decreases monotonically; the effective Hall mobility has a more complicated dependence, exhibiting a maximum at a temperature of about 40°C. By analysing the carrier excitation mechanism it is proposed that in the films studied three donor excitation levels exist, the first one (ΔE=0.025 eV) corresponding to the impurity atoms, and the second (ΔE=0.14 eV) and third (ΔE=0.4 eV) to the divalent selenium vacancies. The donors are assumed to be compensated by some acceptor centres. The model allows the great variety in nm=f(1/T) curves to be explained and gives useful information about the carrier excitation mechanism involved.

A comparison between the transconductances of polycrystalline and monocrystalline TFT's and the relation for optimal grain size with regard to the TFT transconductance are presented.

The influence on the transconductance of thin film transistors of all possible scattering mechanisms is discussed theoretically and it is shown that the most suitable one is intergrain barrier scattering. The theoretical results have been proved on physical model samples and on the practical thin film transistor (TFT).

A method for the determination of surface potential and occupied surface states concentration of semiconductor thin films is given using MIS capacitance. In the case of films with ratios of the geometrical thickness d to Debye length LD greater than 5, it is possible to use the method valid for samples with semi-infinite geometry while in the opposite case a correction must be introduced containing the influence of the second surface and of the finite film thickness. Finally the limits of the MIS capacitance method for the determination of the basic thin film surface properties are shown. Es wird eine Methode für die Bestimmung des Oberflächenpotentials und der Konzentration der besetzten Oberflächenzustände von dünnen Halbleiterschichten mit Hilfe der MIS Kapazitätsmethode angegeben. Im Falle, daß das Verhältnis der geometrischen Schichtdicke d zur Debye-Länge LD größer als 5 ist, ist es möglich, die Methode der MIS Kapazität in der Form, wie sie für die Geometrie des unendlichen Halbraumes gültig ist, zu verwenden. Im entgegengesetzten Falle muß eine Korrektur, die den Einfluß der zweiten Oberfläche und der geometrischen Schichtdicke enthält, eingeführt werden. Schließlich werden die Beschränkungen der MIS Kapazitätsmethode für die Bestimmung der wesentlichen Oberflächeneigenschaften dünner Halbleiterschichten diskutiert.