We propose a double channel mechanism for the formation of charged excitons (trions); they are formed through bi- and tri-molecular processes. This directly implies that both negatively and ...positively charged excitons coexist in a quantum well, even in the absence of excess carriers. The model is applied to a time-resolved photoluminescence experiment performed on a very high quality InGaAs quantum well sample, in which the photoluminescence contributions at the energy of the trion, exciton and at the band edge can be clearly separated and traced over a broad range of times and densities. The unresolved discrepancy between the theoretical and experimental radiative decay time of the exciton in a doped semiconductor is explained.
We present the results of a detailed time resolved luminescence study carried
out on a very high quality InGaAs quantum well sample where the contributions
at the energy of the exciton and at the ...band edge can be clearly separated. We
perform this experiment with a spectral resolution and a sensitivity of the
set-up allowing to keep the observation of these two separate contributions
over a broad range of times and densities. This allows us to directly evidence
the exciton formation time, which depends on the density as expected from
theory. We also evidence the dominant contribution of a minority of excitons to
the luminescence signal, and the absence of thermodynamical equilibrium at low
densities.
Phys. Rev. B 61, R10575 (2000) Direct experimental evidences for excitonic lasing is obtained in optically
pumped V-groove quantum wire structures. We demonstrate that laser emission at
a temperature ...of 10 K arises from a population inversion of localized excitons
within the inhomogenously-broadened luminescence line. At the lasing threshold,
we estimate a maximum exciton density of about 1.8 105cm-1.
We present the results of a detailed time resolved luminescence study carried out on a very high quality InGaAs quantum well sample where the contributions at the energy of the exciton and at the ...band edge can be clearly separated. We perform this experiment with a spectral resolution and a sensitivity of the set-up allowing to keep the observation of these two separate contributions over a broad range of times and densities. This allows us to directly evidence the exciton formation time, which depends on the density as expected from theory. We also evidence the dominant contribution of a minority of excitons to the luminescence signal, and the absence of thermodynamical equilibrium at low densities.
Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quantum wire structures. We demonstrate that laser emission at a temperature of 10 K arises from a ...population inversion of localized excitons within the inhomogenously-broadened luminescence line. At the lasing threshold, we estimate a maximum exciton density of about 1.8 105cm-1.
