Characterisation of oxygen and oxygen-related defects in highly- and lowly-doped silicon

In this paper, an overview will be given about analytical techniques which are suitable for the study of oxygen and oxygen precipitation in highly- and lowly-doped silicon. It will be shown that in the case of highly-doped silicon, the application of Fourier Transform Infrared (FT-IR) absorption spectroscopy requires the use of ultra-thinned or high-fluence irradiated samples and a dedicated data analysis. This sample preparation is necessary to reduce the free carrier absorption in the mid-IR region. It is shown that besides the interstitial oxygen concentration [Oi] and the amount of precipitated oxygen, it is possible to determine the stoichiometry of oxygen precipitates from the study of the corresponding absorption bands. Oxygen precipitation in p+ silicon can also be investigated by the D1–D2 lines in photoluminescence (PL) on as-grown or heat–treated material without special sample preparation. In oxygen-doped high-resistivity float-zone silicon, standard FT-IR analysis can be applied to determine [Oi]. The presence of oxygen-related shallow donors can be probed by a combination of electrical (spreading resistance probe, SRP; capacitance–voltage, C–V) and (quasi-)spectroscopic techniques (deep-level transient spectroscopy, DLTS).