Advanced lifetime spectroscopy - Defect parameters of iron in silicon and a new fingerprint
Abstract
As dissolved iron is one of the most common lifetime-killing contaminants in silicon, its coexisting defect configurations, interstitial iron (Fe(ind i)) and iron-boron pairs (FeB), are investigated on an intentionally iron-contaminated silicon sample by means of temperature-dependent and injection-dependent lifetime spectroscopy (TDLS and IDLS). In good agreement with the literature, the study identifies the known Fe(ind i) donor level at E(ind t)-E(ind V) = (0.394 +- 0.005) eV and determines its symmetry factor as k = sigma(ind n) / sigma(ind p) = 51 +- 5, which is an order of magnitude lower than expected from the literature. Using the well-confirmed k factor, the poorly-confirmed electron capture cross-section is re-determined as sigma(ind n) = (3.6 +- 0.4)×10(exp -15) cm2 at 300 K. The observed exponential sigma(T)-dependence identifies the multiphonon emission mechanism as the dominant capture mechanism for electrons with an activation energy E(ind ?) = 0.024 eV. Moreover, the study reveals an additional fingerprint of iron which consists in a qualitative change of the TDLS curve upon illumination and its S-like shape under dark conditions. Based on this robust criterion, iron is identified as the limiting impurity in a standard industrial multicrystalline silicon sample.
