Three-electrode micro-discharge device: ions injection from the stationary townsend discharge

The using a three-electrode system “semiconductor-gas discharge” as a microreactor for surface plasma chemical treatment of semiconductor materials was studied. The system consists of two discharge gaps separated by a metal grid, which is the common electrode. A stationary self-sustained Townsend discharge is formed in the first gap. Charged particles, passing through the grid cells, excite a non-self-standing discharge in the second gap. Treatment of the sample surface occurs as a result of interaction with the discharge products. The experiments were carried out with an argon-filled system, and GaAs was used as a sample. The change of surface properties was determined by the method of spectral ellipsometry. It is shown that irradiation of the semiconductor with argon ions Ar$^+$ result in the surface cleaning from the oxide layer and the formation of a modified near-surface layer 5–20 microns thick. The composition of the layer is a mixture of crystalline and amorphous GaAs.