Absorption Saturation Energy Density of InGaAs-InAlAs Multiple Quantum Well under Tensile and Compressive Strain

概要

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Optical absorption saturation density $I_{\text{s}}$ was measured for InxGa1-xAs-In0.52Al0.48As multiple quantum well structures grown on InP (100) substrates by molecular beam epitaxy. Indium composition $x$ was varied from 0.32 to 0.70 so that the quantum well layer was under tensile strain ($x < 0.53$), lattice matched ($x = 0.53$), or compressive strain ($x > 0.53$). Optical measurement was carried out using femtosecond light pulses from the optical parametric amplifier of a mode-locked Ti-sapphire laser amplifier. The density $I_{\text{s}}$ in a sample changed as a function of photon energy and exhibited a minimum value at the band-edge exciton energy. This minimum $I_{\text{s}}$ showed the smallest value at $x=0.46$ (under tensile strain) of all the samples with different $x$. This was in marked contrast to the results reported in the literature. Degenerate pump-probe measurement was also carried out, and the results showed that the relative transmission change $\Delta T/T$ measured at zero delay between the pump and probe pulses exhibited the largest value at $x=0.46$, confirming the result of $I_{\text{s}}$ measurement.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
2005-04-10