Measurement of Carrier Lifetimes in Germanium and Silicon

The decay of photoconductivity has been used to measure the lifetime of excess carriers in rectangular samples of germanium and silicon. The sample is illuminated by a short pulse of light and the sample lifetime obtained from an oscilloscope display of the decay of photoconductivity. Analysis of the solution of the diffusion equation yields methods of measuring the bulk lifetime, the surface recombination velocity, and the diffusion constant.