Temperature and compositional dependence of optical and optoelectronic properties in Ce3+-doped Y3Sc2Al3−xGaxO12 (x = 0, 1, 2, 3)

Abstract

The temperature and compositional dependence of luminescence and photoconductivity were studied in Ce3+-doped garnet ceramics with the compositions of (Ce0.005Y0.995)3Sc2Al3−xGaxO12 (x=0, 1, 2, 3). With increasing Ga content in the garnet host, the Ce3+ luminescence from the lowest 5d level (5d1) was blue-shifted because the crystal field splitting of the 5d levels decreased. In addition, the quantum yield of the Ce3+ luminescence at 300K decreased and the luminescence quenching temperature of the Ce3+ luminescence decreased with increasing Ga content. Although a photocurrent was not observed in the x=0 sample even at 600K, the photocurrent excitation bands corresponding to the lowest (5d1) and the second lowest (5d2) 5d levels were observed in the Ga-substituted garnet samples (x=1, 2, 3) even at lower temperatures. Following the analysis of the activation energy of the photocurrent, the relative energies of the Ce3+ 5d levels and the conduction band of the garnet host are discussed.