Luminescence Circular Polarization of AgGaSe2 on Excitation of Circularly Polarized Light

Abstract

Luminescence circular polarization on the optically isotropic face of the AgGaSe2 crystal, (001), is studied using a pulsed-dye laser. The photon energies of the pulsed-dye laser are set to 1.89 eV, 2.12 eV and 2.75 eV so as to excite the electrons to the lowest conduction band from the uppermost valence band, the upper two valence bands and all three valence bands, respectively. The luminescence circular polarization for excitation at 1.89 eV shows the opposite sign to that for excitation at 2.12 eV, as expected from the quasi-cubic model, but the maximum degree of luminescence circular polarization, 15%, is much smaller than the predicted value. It is confirmed that the built-in lattice compression diminishes the intensity of the transition probability for circularly polarized light on the optically isotropic face.