Identification of the dynamics of plasma‐induced damage in a CuInSe2 thin film by fractal processing

A planar ionization system for rapid visualization and recording the resistance inhomogeneity and photoconductivity distribution in a chalcopyrite‐type semiconductor (CuInSe₂) copper‐indium‐diselenide film is studied. A part of the discharge energy is transferred to the electrodes of the system by the bombardment of the electrode surface due to an electron‐ion flow. This process leads to the sputtering mechanism of the electrode surface material. It is shown that the plasma‐induced damage (PID) in a CuInSe₂ thin film was primarily due to the effectiveness of sputtering and physico‐chemical interactions in the discharge gap during the transition from Townsend to the glow type. At the same time a nondestructive method is suggested for the analysis of the dynamics of PID in the CuInSe₂ thin film by fractal processing in the planar ionization system. Some properties of the device have been evaluated, such as a relative change of the resistance inhomogeneity is determined by a relative change of discharge light emission (DLE) intensity when a current is passed through an ionization cell. For the quantitative analysis of the change in the dynamic feature of PID of CuInSe₂ thin films, fractal dimension analysis was used following the records of the DLE intensity. The quality of the film was analyzed using both the profile and spatial distributed DLE intensities data showing the surface inhomogeneity and damage in the thin film as function of time. Thus, by using fractal concept, the order of the surface damage and the quality of the CuInSe₂ as function of time can be assessed exactly and the size and location of the surface inhomogeneities in thin film to be ascertained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)