Carrier Lifetime Analysis by Photoconductance Decay and Free Carrier Absorption Measurements

High-power devices require a thick silicon layer with high resistivity to achieve high breakdown voltages. In order to optimize the turn-on and turn-off behavior of these devices, precise adjustment of the carrier lifetime is necessary, together with knowledge of its dependence on process parameters and operation conditions (e.g., temperature and injection level). We have therefore analyzed the carrier lifetime of the starting material (float-zone silicon) as well as processed devices that have both been either doped with transition metals (Pt, Au, Fe) or irradiated with electrons, using two different measurement techniques based on photoconductivity decay and free carrier absorption measurements.