Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

Abstract

We study the carrier-density-dependent recombination dynamics in m-plane InGaN/GaN multiple quantum wells in the presence of n-type background doping by time-resolved photoluminescence. Based on Fermi's golden rule and Saha's equation, we decompose the radiative recombination channel into an excitonic and an electron-hole pair contribution, and extract the injected carrier-density-dependent bimolecular recombination coefficients. Contrary to the standard electron-hole picture, our results confirm the strong influence of excitons even at room temperature. Indeed, at 300 K, excitons represent up to 63 ± 6% of the photoexcited carriers. In addition, following the Shockley-Read-Hall model, we extract the electron and hole capture rates by deep levels and demonstrate that the increase in the effective lifetime with injected carrier density is due to asymmetric capture rates in presence of an n-type background doping. Thanks to the proper determination of the density-dependent recombination coefficients up to high injection densities, our method provides a way to evaluate the importance of Auger recombination.

Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures

“…12,13 While excitons in GaN-based nanostructures have relatively high binding energies and small Bohr radii 21 (as compared to GaAs-based structures) and thus could exhibit quantum properties at higher temperatures, 22 the additional challenges that must be faced to achieve such degree of control are numerous. These may include nonradiative losses, 23 megavolt per centimeter-strong built-in electric fields, 24 an exponential dependence of the lifetime on the exciton density under high excitation conditions, [25][26][27] and the guided-and-scattered light that must be distinguished from the exciton photoluminescence (PL). 17,28 In this letter we overcome those challenges and report on the realization of ∼ 10 µm ×50 µm-size thermalized exciton fluid, trapped in the plane of a GaN/(GaAl)N quantum well grown on a free-standing GaN substrate.…”

Broadband, High‐Speed, and Large‐Amplitude Dynamic Optical Switching with Yttrium‐Doped Cadmium Oxide

“…The fits for the LD, MD, and HD samples are presented in Section S4 in the Supporting Information. The strong dependence of the time constants on the pump fluence points to recombination processes like Auger recombination, which is typical for semiconductors with large carrier densities …”

Free chargesversusexcitons: photoluminescence investigation of InGaN/GaN multiple quantum well nanorods and their planar counterparts

“…20,21 Given the large exciton binding energy in InGaN quantum wells due to a strong quantum confinement effect, 22 the presence of both free carriers and excitons should be considered in density dependent carrier dynamics studies, which has recently been suggested. 12,23,24 Even at room temperature, a rapid formation of excitons results in a significant exciton fraction in the total carrier population in InGaN quantum wells, as quantitatively calculated by Hangleiter et al 24 Blancon et al recently 25 proposed that the lower energy states at the layer edges/surface area of perovskite nanoplatelets could directly facilitate exciton dissociation.…”

“…6,[9][10][11] However, detailed analyses of carrier dynamics are still unable to explain the change in luminescence properties of MQW nanorods over planar layers with respect to their carrier density dependence. [12][13][14][15] In particular, the impact of the significant increase of surface states in nanorods is not fully understood. A significant enhancement in the PL efficiency of nanorods is in contrast to the fact that enhanced non-radiative recombinationexpected in nanorods due to surface damage is actually detrimental to the radiative efficiency.…”