Absolute external photoluminescence quantum efficiency of the1sorthoexciton inCu2O

Abstract

The photoluminescence quantum efficiency of the yellow series 1s orthoexciton in Cu 2 O, including its phonon sidebands, was measured in an Ulbricht sphere. The obtained efficiency values between 10 Ϫ4 and 10 Ϫ6 are remarkably low. The nonmonotonous temperature dependence is analyzed.

Midinfrared properties of cuprous oxide: High-order lattice vibrations and intraexcitonic transitions of the1sparaexciton

“…6͑b͔͒. In fact this is exactly what one would expect for the 1s para-exciton: since an interconversion mechanism 9 between the two 1s species is generally accepted to explain the temperature dependent 1s ortho population, 8 our findings fit well into that picture. Even the slight maximum of the 1s para density at T Ϸ 15 K coincides with the corresponding minimum of the 1s ortho population.…”

“…While the 1s ortho-exciton is quadrupole allowed, the 1s para-exciton is optically one-photon forbidden in all orders of perturbation theory. Apart from one emission line of almost negligible efficiency, 8 the 1s paraexciton is also unable to decay via phonon assisted luminescence. Disregarding high density effects, the two dominant loss mechanisms are impurity recombination and phonon assisted conversion into 1s ortho-excitons.…”

Study of the 1s orthoexciton luminescence in Cu2O under two-photon excitation

“…Although the direct emission decreases with increasing temperature, it does not show a large rise at low temperatures for the case of 2s excitation. A similar temperature dependence of the phonon-assisted emission for 1s orthoexcitons excited by a 514 nm laser has been reported and was explained by thermal activation from the lower lying paraexciton state [19,20]. At high temperatures, the orthoexciton density is expected to be proportional to e ÀDE=k B T ; where DE is the energy difference between the two levels.…”

Exciton transport in Cu2O, exciton detection by field ionization in a Schottky barrier and intraexcitonic transitions

“…It turned out, that the signal is one order of magnitude stronger under excitation of the LO phonon assisted absorption continuum of the 1s ortho exciton than under excitation above the band gap. The induced absorption increases with increasing excitation intensity, disappears if Zu exc falls below the LO-phonon absorption band of the 1s ortho exciton, broadens with increasing lattice temperature and shows also with increasing lattice temperature a nonmonotonous dependence complimentary to the luminescence yield of the 1s ortho exciton [20].…”