The dependence of electronic properties of a deep level on electric field is relevant for better understanding of its impact on device characteristics. However, direct observation of the field assisted free carrier capture in DLTS is difficult, since in filling pulse experiments, during the applied pulse, no electric field is expected in the neutral part of the semiconducting substrate. For this reason isothermal DLTS measured as a function of pulse duration is an accurate technique to determine capture cross-sections in absence of electric field. On the other hand, when observing the emission of a carrier in conventional DLTS, an electric field ís present.
In this work we applied the double pulse DLTS technique to measure the emission rates of Fe(2-/-) for different temperatures and electric fields. Data analysis revealed that an electric field affects the emission rate mainly through the pre-exponential factor, which is proportional to the capture cross section. An empirical electrical field dependence of the electron capture cross section for a negatively charged iron impurity was deduced
