Independent determination of carrier densities and analysis of different recombination channels in GaAs PL and EL through Raman scattering of LO phonon – plasmon coupled mode

Determining the carrier (electron) density n is critical in many material and device characterization. An ABC model is widely used to describe the carrier recombination, where the contributions of non-radiative, radiative, and Auger recombination are partitioned, respectively, into the three terms in R = An + Bn² + Cn³. In general, not only the partition is questionable, e.g., nonradiative contribution could be non-linear in n, but also a number of approximations are needed in order to determine n. It has been demonstrated recently that by combining photoluminescence (PL) and Raman imaging one can simultaneously obtain the spatial distribution of electron and hole density in a semiconductor material or device by first determining the electron density through Raman scattering of LO phonon – plasmon coupled (LOPP) mode [1]. This approach is extended to analyze carrier recombination processes in both PL and electro-luminescence (EL) with varying laser excitation and current injection level. The results indicate that nonradiative recombination typically exhibits non-linear dependence on n, as suggested by a recent analysis of EL in an InGaN LED [2].
[1] C. Hu et al., Light: Sci. & Appl. 7, 23 (2018).
[2] T. Gfroerer, J. Appl. Phys. 125, 204502 (2019).