A device for free-carrier recombination lifetime measurements

The design of a microwave system, the user interface, and the basic characteristics of noncontact equipment for measuring the recombination lifetime of free charge carriers in semiconductor materials by the photoconductivity-decay method are described. The features of the microwave-system design eliminate the need for a microwave circulator and other expensive elements of the systems without a loss in the equipment sensitivity. This substantially simplifies the design and provides automated measurements of the free-carrier lifetime in silicon single crystals in a range of 0.2 μs to tens of milliseconds. The upper measurement limit is determined by the geometrical dimensions of a sample and the surface treatment quality. The results of measuring the photoconductivity relaxation time in reference single-crystal silicon samples are presented.