Time-resolved microwave technique for ultrafast charge-carrier recombination time measurements in diamonds and GaAs

Recombination times of laser-excited charge carriers in natural diamond cry stals, polycrystalline chemical vapor deposited (CVD) diamond films, and Ga As wafers were measured with 1 ns time resolution by a microwave-radiation technique. A waveguide scheme was applied to record time-dependent reflecti on and transmission of 140 GHz cw radiation. The measured recombination car rier lifetimes in the bulk of natural and CVD diamond samples were found to be of 1-3 ns. In GaAs, a distinguishing difference between the bulk (15 ns ) and surface (3.5 ns) recombination times was observed. To validate the ap plicability of the developed technique, a computer simulation of the microw ave-radiation interaction with excited plane-parallel specimens has been pe rformed applying the Fabry-Perot resonator theory and the classical Drude m odel. (C) 1999 American Institute of Physics. [S0003-6951(99)02312-8].