Optical properties of Cd(Ga _{1– x} Tm _x ) ₂ S ₄ ( x = 0.01) single crystals

Abstract

Photoluminescence and absorption spectra of Cd(Ga 0.99 Tm 0.01 ) 2 S 4 single crystals were investigated. We observed a broad and weak emission band at 4600Å, a relatively strong emission band at 6200Å, and several sharp and narrow emission bands in the wavelength region of 7600 to 8400Å in the photoluminescence spectrum at 4.8 K. The two broad emission bands observed in shorter wavelength regions correspond to donor-acceptor pair recombination. The ten sharp and narrow emission bands observed in the near infrared region are associated with the 3 F 4 → 3 H 6 transitions of Tm 3+ ions. These bands were also observed in the optical absorption spectrum for the crystals. Twelve-absorption bands showed a difference from the emission bands in positions. The emission and absorption bands related to Tm 3+ ions were discussed on the basis of crystal-field theory.