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This paper surveys recent work on the oxide cathode. This work points to a physical model of the oxide cathode in which (1) current is carried through the cathode by semiconduction through the oxide and by pore conduction through the interstices between oxide particles, (2) both conduction process are controlled by the properties of the semiconducting oxide, (3) the oxide is activated by the production of electron donors, (4) the donors, as well as other constituents of the oxide, are mobile at the normal operating temperature of the cathode, and (5) electrolysis of the donors limits the density of free electrons available for conduction near the emitting surface and the density of free electrons available for emission at the emitting surface. [ABSTRACT FROM AUTHOR]

The present paper deals with something about the influence of adsorbed impurity centres on the electrical properties of germanium and silicon. After a historical review and an introduction to the fundamental conceptions (§ 2), the essential properties of semiconductor surfaces are discussed. § 3 deals with surface recombination and after an illustration of the term of surface recombination velocity summarizes measuring methods and experimental results; furtheron, the influence on the electrical behaviour of rectifiers and transistors is discussed, and finally, the effective surface recombination is dealt with. § 4 contains a review of measuring methods and experimental results on work function and contact potential. § 5 describes the surface conduction, particularly the channels. § 6 reviews the surface model of Brattain and Bardeen, commonly used for the explanation of surface properties. In the following chapters, the physical properties of surfaces are, under simplified conditions, treated quantitatively, and, as far as possible, illustrated by experimental examples. In § 7, the occupation of surface terms under thermal equilibrium as a function of density and energy level is derived, and work function and surface conductivity, including field effect, are discussed. § 8 deals with surface recombination, i. e. with electron transitions between surface levels and energy bands. § 9 describes the theory of work function under the influence of ligth as developed by Brattain and Bardeen. Finally, § 10 deals with the special properties of channels, namely, with Schrieffer's theory of carrier mobility in channels, on one side, and the channel conductivity parallel to the surface, on the other. § 11 discusses the influence of channels on the dc and ac behaviour of rectifiers and transistors as far this is possible today. [ABSTRACT FROM AUTHOR]

In this paper, the mutual interactions, leading to additional attractive or repulsive forces, between material lattice defects in (preferentially ionic) crystals are reviewed from the point of view of the theory of thermal disorder founded by Frenkel, Schottky and Wagner. At first the physical nature of the possible forces and their types of force law (wide or low range) are discussed. Of these, Coulomb and chemical (valence) interactions seem to be of much higher importance than those created by different polarizabilities, by elastic distortion of the lattice or by lattice vibrations. Values of binding energies known from detailed calculations or experimental data are reported. Then the methods of calculating the thermal equilibrium of the defects are critically studied. Starting from the well-known concepts of association (especially adapted to low range forces) and of the Debye-Hückel ionic cloud (successful in the theory of strong liquid electrolytes), it is shown that a combination of both will approximate best the real equilibrium of interacting defects in ionic crystals and semiconductors, an exact description lacking until now for higher than "infinitely small" concentrations of defects. This combined theory is essentially identical with one advanced by Bjerrum for aqueous electrolytes. Also in crystals, the Bjerrum critical radius will reasonably separate between associated defects and those belonging to the ionic cloud. Owing to the comparatively small dielectric constant in most of the crystals, the second region here generally is of small importance. To extend the validity of the calculations towards higher defect concentrations seems still highly desirable. After outlining the non-equilibrium states of defects, the methods of experimental detection of defect interactions are briefly described, summarizing the most important results. These methods include ionic conductivity, self diffusion and diffusion of foreign ions, dielectric loss, optical absorption and its successive phenomena (luminescence, photochemical reactions), and magnetic methods (nuclear resonance). [ABSTRACT FROM AUTHOR]