Eur. Phys. J. AP 2, 267–273 (1998) THE EUROPEAN PHYSICAL JOURNAL APPLIED PHYSICS c  EDP Sciences 1998 Characteristic features of an ionization system with semiconducting cathode B.G. Salamov 1, a ,S¸. Altındal 1 , M. ¨ Ozer 1 , K. ¸ Colako˘glu 1 , and E. Bulur 2 1 Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Teknikokullar, Ankara, Turkey 2 Physics Department, Middle East Technical University, 06531 Ankara, Turkey Received: 24 March 1997 / Revised: 7 October 1997 / Accepted: 2 March 1998 Abstract. The characteristic features of a dc discharge generated between parallel plate electrodes and especially the discharge stabilization by the GaAs semiconducting cathode in such a system are studied. The cathode was irradiated on the back-side with IR light in a particular wavelength range that was used to control the photoconductivity of the material. The semiconductor material was found to stabilize the discharge. The current-voltage and radiation-voltage characteristics of the gas discharge cell with a semiconducting cathode were obtained experimentally. An investigation of the effect of the voltage amplitude on the dynamics of transient processes in the plane semiconductor-discharge gap structure was made for explanation of the light intensity and current decay. Expressions are obtained for the photoelectric gain. PACS. 52.80.-s Electric discharges – 73.40.Sx Metal-semiconductor-metal structures 1 Introduction Electronic phenomena that occur at a contact between a semiconductor and a gas discharge plasma with negligible or no erosion and mass transfer have a number of special features and have been among the least investigated semi- conductor contact phenomena. Penetration of a double electrical layers charge into the interior of a semiconduc- tor results in a strong dependence of the value and spatial distribution of the current density on the state of the semi- conductor and makes it possible to control both the cur- rent and the radiation emitted by the gas discharge. Pho- tographic system with semiconducting cathode have found interesting applications in the last decade, especially in the registration of IR images. Rapid control of resistivity inhomogeneities in semiconductor plates are other inter- esting utilizations of the these systems. The study of the above system parameters is also important for practical use of the stable discharge [1–3]. A reduction in the gas gap in a system formed by a semiconductor and a gas-discharge plasma considerably broadens the region of spatial stabilization of the current in the system, both with respect to the gas pressures and in respect to the permissible applied voltages [4]. This is desirable in the case of some practical application relating to visualization of the spatial distribution of the current density in photosensitive semiconductor materials [5], be- a On leave from Physics Department, Baku State University, 370145 Baku, Azerbaijan e-mail: bala@quark.fef.gazi.edu.tr cause it enhances the resolution [6], facilitates technical realization of reliable operation, and widens the range of the materials employed. The complete pattern of the pro- cesses in a gas-discharge cell with a small gap cannot be interpreted satisfactorily on the basis of a simple theory of gas discharge [7–9] and requires allowance for the fac- tors that relate to the processes of the gas discharge glow from the actual surface of a semiconductor cathode. In the system cell the current density can be increased lo- cally by illuminating the photoconducting semiconductor in the range of its sensitivity. This is followed by increasing the brightness of the discharge glow in the visible spectral range. In this paper the results of an experimental study of the mechanism of the current under the indicated condi- tions for the semi-insulating GaAs semiconductor cathode are presented. The main purpose of this research is to study the effect of the voltage amplitude on the dynamics of transient pro- cesses in the plane semiconductor-discharge gap structure without changing other experimental parameters, e.g., gas pressure or the width of the gas discharge gap. 2 Experimental technique The current-voltage and radiation-voltage characteristics (CVC and RVC) of the gas discharge cell with a semicon- ducting cathode are obtained experimentally as function of the gas pressure. Scheme of the gas discharge cell with semiconducting cathode is given in Figure 1. In all cases after a gas breakdown an increase in the voltage ensured