Long coherent dynamics of localized excitons in (In,Ga)N/GaN quantum wells

Authors :: Poltavtsev, S. V.
Solovev, I. A.
Akimov, I. A.
Chaldyshev, V. V.
Lundin, W. V.
Sakharov, A. V.
Tsatsulnikov, A. F.
Yakovlev, D. R.
Bayer, M.
Source :: Phys. Rev. B 98, 195315 (2018)
Publication Year :: 2018
Abstract: We study the coherent dynamics of localized excitons in 100-periods of 2.5 nm thick (In,Ga)N/GaN quantum wells with 7.5% indium concentration, measured with spectroscopic resolution through two-pulse and three-pulse photon echoes at the temperature of 1.5 K. A long-lived coherent exciton dynamics is observed in the (In,Ga)N quantum wells: When the laser photon energy is tuned across the 43 meV-wide inhomogeneously broadened resonance line, the coherence time T2 varies between 45 and 255 ps, increasing with stronger exciton localization. The corresponding narrow homogeneous linewidths ranging from 5.2 to 29 {\mu}eV as well as the relatively weak exciton-phonon interaction (0.8 {\mu}eV/K) confirm a strong, quantum dot-like exciton localization in a static disordered potential inside the (In,Ga)N quantum well layers.<br />Comment: 4 figs