Characterization of SrS evaporated materials grown from a new high temperature source with a carbon heater

Abstract

Strontium sulfide (SrS) was used as the evaporant material to prepare the phosphor layer for a blue electroluminescent (EL) element. SrS evaporation was performed by using a resistively heated carbon heater. No heat treatment of the phosphor layer after deposition was made. A crucible temperature of more than 1400 °C was obtained in this evaporation system which makes this system equally applicable for the evaporation of other materials with high melting temperature. Cerium (Ce) luminescent centers were doped in SrS films and a Ce concentration of 0.3 mol % was determined to be optimum for EL. For SrS:Ce films deposited onto a quartz substrate, x-ray diffraction and photoluminescent measurements indicated an optimum substrate temperature (Tsub) of 500 °C. In the EL fabrication process, Tsub was restricted to ≦410 °C by the softening temperature of the alumino-silicate substrate used in the EL device.