Behaviour of current in a planar gas discharge system with a large-diameter semiconductor cathode

Abstract

Gas breakdown in air in a planar gas discharge system was studied experimentally at various distances L between the electrodes and different diameters R of the electrode areas of the semiconductor cathodes. The cathode was irradiated on the back-side with light in a particular wavelength range that was used to control the photoconductivity of the material. The current–voltage characteristics of the gas discharge system with a large-diameter GaAs semiconductor cathode were studied in a wide range of the gas pressure p (28–550 Torr), interelectrode distances L (45–330 μm), and conductivities of the cathode. We show that for all experimental conditions the current density increases over the entire range of voltages U>Udc as the diameters R of the electrode areas increase. It is shown that, for arbitrary geometric dimensions of the semiconductor cathode (in the range of L/R under investigation), the ratio of the breakdown electric field to the gas pressure holds constant (Edc/p)min≈const. at the breakdown curve minimum. The breakdown voltage Udc is a function of both the product of the gas pressure p by the distance L and the ratio L/R (Udc = f(pL,L/R).