2025/05/20 by Daniel O. Siebadji Tchuimeni, Marc Ziégler, Tchuimeni, Daniel O. Siebadji +11
Materials Science · #FOS: Physical sciences #Ga2O3 and related materials #Magnetic and transport properties of perovskites and related materials #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Optics (physics.optics) #ZnO doping and properties
paper · pdf · doi:10.48550/arxiv.2505.14056
openalex publication_date 2025/05/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We investigate the ultrafast dynamics of excitons in a 2.6 nm-thick \mathrmZnO/Zn0.84Mg0.16O quantum well grown on a c-axis sapphire substrate, using non-degenerate time-resolved pump-probe spectroscopy. A pump pulse at 266 nm generates photocarriers within the ZnMgO barriers, and their dynamics is monitored through time-resolved differential reflectance measurements using a supercontinuum probe spanning the 345-400 nm spectral range. Photocarriers generated in the barriers rapidly relax into the quantum well, where they form excitons within sub-picosecond timescales. These excitons quickly thermalize and become localized, likely due to interface disorder or well-width fluctuations, as supported by photoluminescence measurements showing a clear Stokes shift and the absence of free exciton emission. A phonon-assisted absorption process, leading to the effective thermalization of excitons, is observed and analyzed. We identify moreover a negative differential reflectance feature as a photoinduced absorption into a biexciton state, with a binding energy ranging from 18 to 22 meV depending on temperature.