Auger recombination dynamics of lead salts under picosecond free-electron-laser excitation

Pump-probe transmission experiments have been performed on PbSe above the f undamental absorption edge near 4 mu m in the temperature range 30 to 300 K , using the Dutch ps free-electron laser. For temperatures below 200 K and carrier densities above the threshold for stimulated emission, stimulated r ecombination represents the most efficient recombination mechanism with rel atively fast kinetics in the 50-100-ps regime, in good agreement with earli er reports of photoluminescent emission. Above this temperature Auger recom bination dominates, and the Auger coefficient C is determined from the pump -probe decay curves. In the low-temperature regime the Auger coefficient is determined from the decay curves at times beyond 100 ps. The Auger coeffic ient is approximately constant (with a value of about 8 x 10(-28) cm(6) S-1 ) between 300 and 70 K, and then drops a value of about 1 x 10(-28) cm(6) S -1 at 30 K, in good agreement with the theory for nonparabolic near-mirror bands and nondegenerate statistics. It is found that C for PbSe is between one and two orders of magnitude lower than for Hg1-xCdxTe of comparable ban d gap. [S0163-1829(98)07243-9].