AN IMPROVED ANALYSIS OF ADMITTANCE DATA FOR HIGH RESISTIVITY MATERIALS BY A NONLINEAR REGULARIZATION METHOD

Admittance data of GaAs Schottky diodes are analyzed in order to calculate the activation energy and the cross section of deep levels. An improved model for high resistivity semiconductor material is introduced. In this model the admittance depends nonlinearly on the distribution of the relaxation times of the deep levels and on material parameters like the resistivity, the barrier height, and the band gap of the semiconductor. The reconstruction of a continuous distribution and of the parameters from experimental admittance data is an ill-posed inverse problem which is solved by a nonlinear regularization procedure. The method is used to analyze the deep levels and the semiconducting properties of a semi-insulating GaAs diode. Values for the resistivity, the barrier height, and the band gap could be confirmed and deep levels with activation energy in the range of 0.5–0.72 eV were determined to be electrical active.