DETERMINATION OF RECOMBINATION PARAMETERS IN SILICON-WAFERS BY TRANSIENT MICROWAVE-ABSORPTION

Principles of measurement of photoconductance transients by time-resol ved microwave absorption and reflection mode are presented. The microw ave transmission (absorption) mode is a new implementation of the time -resolved microwave conductivity method. This instrument is more sensi tive with respect to microwave response signal and less critical to in stabilities induced by phase modulation of the response. An adjustment of the measurement system into a local resonance for each particular sample under investigation and the whole set of experimental condition s is crucial to ensure the highest sensitivity and reliability of the instruments. The waveguide slot resonance antenna provides mapping of recombination parameters in silicon wafers of thickness d greater than or equal to 50 mu m and resistivity rho > 1 Omega cm with a spatial r esolution of 1-2 mm. Theoretical models and validity of the approximat ions for carrier decay analysis and determination of the recombination parameters are discussed. The nonlinearities of the recombination pro cesses (Shockley-Read-Hall, Auger type, or carrier trapping) arising a t the moderate and high level of excitation are analyzed. Determinatio n of the recombination parameters in this case is based on correlated measurements and numerical simulations taking into account the dominan t recombination mechanisms. The activation energies of carrier traps E (tb) = 0.16 +/- 0.02 eV and E(ts) = 0.20 +/- 0.02 eV in neutron transm utation doped n-Si material have been derived from temperature depende nt carrier lifetime measurements. (C) 1996 American Institute of Physi cs.