Luminescence in β-ZnP₂ at Low Temperatures - Intersystem Spin Conversion of Exciton Polaritons -

Abstract

Various aspects of luminescence in β-ZnP₂ have been investigated at low temperatures. Formation of exciton molecules is confirmed under the CW resonance excitation into the lowest 1s triplet exciton absorption band. The exciton molecule emission band M appears at a moderately weak laser power. Low energy component C_L1 of the singlet luminescence comes from the anti-Stokes acoustic phonon scattering of the triplet excitons. From the outgoing resonance of the LO Raman line, it is confirmed that the high energy component C_L2 has many strong phonon sidebands, while low energy component C_L1 has no sideband. Furthermore, a novel luminescence C_T resulted from the anti-Stokes scattering of the triplet excitons has been found. From detailed excitation spectra, we can deduce some of the relaxation paths of the exciton polaritons.