Excitonic field screening and bleaching in InGaN/GaN multiple quantum wells

Abstract

Photoinduced carrier dynamics in a sequence of InGaN/GaN multiple quantum wells (MQWs) are studied by employing steady state and ultrafast spectroscopy at room temperature. Time-resolved photoluminescence (PL) measured short carrier lifetimes of , 140 ps at room temperature. Steady state differential transmission was used to measure the in-well field screening due to the photoinjected carriers. The observed offset in emission energy from excitonic screening energies is consistent with the emission of carriers through localized states slightly below the excitonic resonance energy. Furthermore, time-resolved differential transmission with amplified pulses, where significant carrier densities can be optically generated, provides evidence of both excitonic bleaching and field screening in these InGaN quantum wells (QWs). The comparison of the time-resolved differential absorption spectra at various carrier densities allows us to identify different carrier recombination dynamics in the InGaN well and to separate the field screening from the bleaching effects. Finally, the extreme prolongation of the carrier recombination lifetime up to , 4 ms suggests the spatial separation between electrons and holes under the large in-well fields. q

Charge degeneracy removal in the screened hydrogen atom

“…However it is still physically unclear how the screening phenomenon effectively occurs for the excited states of atomic structures where one has noted that a simplified and systematic analytical model is almost entirely absent. Analytical methods for screened atoms are important for studying electronic properties in metalinsulator transitions, charge transport in materials, impurities in semiconductors [30][31][32], charged polymer gels [33][34][35], properties of nanostructures [36,37], molecules adsorbed in metals [38][39][40][41][42][43], hydrogen under pressure, as well as other interesting applications [44][45][46][47][48][49].…”

A roadmap to decipher ultrafast photophysics in two-dimensional nanomaterials

“…51,52 While being less prominent in the literature, photo-induced line narrowing has been reported as a result of carrier-induced screening of parasitic local defect-induced potentials or externally applied and built-in electric fields, see Figure 3b. 34,39,[53][54][55][56][57][58] 2e to a sum of two Gaussians, accounting for the (red markers) A and (blue markers) B exciton, and a polynomial background. 18 Adapted with permission from Reference 18.…”