Time-resolved picosecond infrared absorption induced by high-density photogenerated carriers in Ge and CdSe

摘要: Picosecond time-resolved absorption at 2.2, 3.4, and 3.9 μm produced by photogenerated carriers in intrinsic Ge semi-insulating CdSe has been measured room temperature. For Ge, the peak absorbance changes as square of probe wavelength. The profile a function delay time relative to excitation pulse rises with resolution-limited risetime (< 10 ps) decays over range from several hundred picoseconds nanoseconds. These observations can be accounted for free-carrier Auger recombination. Intervalence transitions make small contribution (∼ 17 percent) induced only 2.2 μm. CdSe, change exhibits more complex profile. Two temporal peaks occur probing wavelengths 3.4 three first occurring about 5 ps after all is due absorption. other have attributed involving impurity (defect) levels trapped carriers.