Light emission in the UV and visible range generated by a planar semiconductor gas discharge system and the possibility of locally increasing the gas discharge light emission (GDLE) in a wide pressure range (2–700 Torr) has been studied. The use of gas discharge gap with microcapillary multichannels spacer (MCS) and an IR light to excite the GaAs photocathode of the system leads to an increase in the GDLE intensity. Electrons entering the multichannels of the discharge gap are multiplied in the electric field by the avalanche mechanism, so that current increases in the discharge gap with microcapillary MCS. In this system the local intensity of GDLE exceeds the intensity of uniform GDLE in the gas discharge system by the same factor as the working area of the photocathode exceeds the total active area of the MCS. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the electric field of our system with the dc Townsend breakdown theory, depending on the pressure range.

Electrical instability in semi‐insulating (SI) GaAs plates of the semiconductor gas‐discharge structure (SGDS) is studied experimentally in air and neon as a function of pressure, interelectrode distance, and cathode area diameter. While being driven with a stationary voltage, it generates current and discharge light‐emission instabilities with different amplitudes of the oscillation in Ne up to atmospheric pressure. The presence of the deep electronic levels of defects, give rise to the N‐shaped negative differential resistance (NDR) of the material, and as a consequence, to oscillations in the discharge light emission when a dc voltage of a high enough magnitude is applied to the GaAs cathode. A SGDS with an N‐shaped current–voltage characteristic (CVC) has been analyzed using both the current and discharge light emission data showing the electrical instability in the GaAs cathode. It is observed that application of high feeding voltage to the cathode gives rise to a nonuniform spatial distribution of the discharge light emission, which disturbed the operation of the system. The experiment also presents a new method to study and visualization of the electrical instabilities in the high‐resistivity GaAs plates of large diameter.