The Scattering of Hot Electrons by Phonons in AlGaN/GaN Quantum Dot

Highly Enhanced Exciton Recombination Rate by Strong Electron–Phonon Coupling in Single ZnTe Nanobelt

“…), free excitons are strongly coupled to LO phonons via Fröhlich interaction, which can lead to a much faster carrier radiative rate than the nonpolar semiconductors. − During a typical intravalley relaxation process, the photoexcited carriers lose their excess energy to crystal lattice by emission of either longitudinal optical (LO) or acoustic phonons, relaxing to the k ∼ 0 momentum states . Since the typical relaxation time for LO and acoustic phonons are on the scale of ∼100 fs to ∼100 ps, respectively, which is much shorter than the exciton recombination time scale (∼1 ns), the emission of a nonequilibrium elementary excitation produces “hot excitons” that have been observed in these polar semiconductors. − The “hot-exciton” emission considerably enhances the radiative rate of the carriers. However, in most of as-reported II–VI semiconductors such as ZnO and CdS, the exciton decay path is still dominated by thermal-equilibrium recombination processes; thus, the decrease of exciton decay rate by electron–phonon coupling is limited, and the exciton lifetime is on the scale of several hundreds of picoseconds or even longer.…”