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Mid-infrared picosecond spectroscopy of MBE indium arsenide epilayers at 300 K

Using a newly developed picosecond mid-infrared double-resonance pump-probe spectrometer carrier recombination and intraband scattering have been studied in a range of high-quality InAs epilayers grown by MBE. In as-grown samples recombination rates are typically dominated by recombination at the InAs/GaAs heterointerface with an interfacial recombination velocity of approximately=2.7*104 cm s-1, but Auger recombination (characterized by an Auger coefficient of 1.1*10-26 cm6 s-1) dominates in the thicker samples at higher excitation levels. At short pump-probe delays dynamic spectral hole burning in the absorption continuum has been seen for the first time. Spectral holes (with typical widths of approximately=300 cm-1) are created at pump pulse intensities of approximately=107 W cm-2 and photon energies 32-57 meV above the band edge. The spectral holes track with the pump intensity and photon energy, and an analysis of their widths and depths gives an estimate of 30-50 fs for the carrier intraband scattering time.