Interband and intraband relaxation dynamics in InSb based quantum wells

We utilize pump/probe spectroscopy to determine the interband and intraband relaxation dynamics in InSb based quantum wells. Using non-degenerate pump/probe techniques, we observed several time scales for relaxation. One time scale tau(3) ranging from 2 ps to 5 ps is due to the intraband relaxation dynamics. Here, both the emission of LO phonons (within the Gamma valley) and carrier scattering between the X, L, and Gamma valleys contribute to the relaxation. An observed longer relaxation time, tau(2) approximate to 20 ps, is attributed to electron-hole recombination across the gap (the interband relaxation time). Finally, using a mid-infrared (MIR) degenerate pump/probe scheme, we observed a very fast relaxation time of similar to 1 ps, which is due to the saturation of the band-to-band absorption. Our results are important for developing concepts for InSb devices operating in the THz or MIR optical ranges with the endless need for faster response. Published by AIP Publishing.