Thermally Stimulated Currents in Semiconductors: Analysis of Rate Equations for a Single-Level Model and Thermally Stimulated Currents in Si

Abstract

Thermally stimulated currents (TSCs) in semiconductors are analyzed theoretically. The rate equations describing TSCs are solved numerically for various heating profiles, which makes it possible to evaluate the ionization energy, concentration, and capture cross section of traps. The slow and fast retrapping approximations are examined for an arbitrary heating profile. A new approach to TSC data processing is proposed: cleaning of a peak from the lower temperature peak by storing the preilluminated material in the dark at the relaxation temperature of the lower temperature peak. It is shown that heating (constant-rate or exponential) followed by isothermal holding makes it possible to determine the ionization energy of traps without knowing the retrapping mechanism. This approach is adapted for the case when the retrapping time is comparable to the carrier lifetime. Partially compensated silicon with impurity photoconductivity is prepared by doping with gold and phosphorus. It is shown that, using resonance photoexcitation, one can identify the nature (electron or hole) of traps and evaluate their ionization energy. The depths and capture cross sections of three trapping centers in Si were evaluated.