Fractal processing for an analysis of the quality and resistivity of large semiconductor plates

Abstract

A nondestructive method is suggested for the analysis of the quality and resistivity inhomogeneity of semiconductor plates in an ionization system with a SI GaAs semiconductor plate. At the same time, a device for rapid visualization and recording the resistance inhomogeneity and photoconductivity distribution throughout the bulk material in high-resistivity and photosensitive semiconductor plates of large diameter (50-100 mm) is described. Semiconductor plates with the resistivity from 10 5 to 10 9 Ωcm can be analyzed in the proposed device. The possibilities of the device have been evaluated, i.e. a relative change of the resistance inhomogeneity is determined by a relative change of discharge light emission intensity when a current is passed through an ionization cell. For the quantitative analysis of quality and resistivity inhomogeneity of semiconductor plates, fractal dimension analysis was used following the records of the discharge light emission intensity. The quality of plates was analyzed using both the profile and spatial distributed light emission intensity data showing the internal inhomogeneity in the semiconductor plate. Thus, by using fractal concept, the surface quality of the high-resistivity semiconductor plate can be assessed exactly and the size and location of the internal inhomogeneities in the semiconductor plate to be ascertained.