Deep level transient spectroscopy on radioactive impurities: Demonstration for Si:111In*

Abstract

A defect specific analysis technique is introduced that combines the high concentration sensitivity of deep level transient spectroscopy (DLTS) with the radioactive transmutation of probe atoms; this technique results in the chemical identification of particular atoms which participate in the observed defect centres. The method is demonstrated for n- and p-type silicon samples, which are implanted with radioactive 111In* ions. The activity of the indium ions decreases with half-life T1/2 of 2.83 d by a decay into stable cadmium ions. A series of Cd-related levels whose concentrations increase exponentially with the decay time of 111In* are identified in the DLTS spectra. Cd-diffused silicon samples are investigated for comparison; these samples reveal similar DLTS spectra. The analysis method described can be extended to all semiconductors and to a variety of radioactive probe atoms.