The relation between luminous properties and oxygen content in ZnS:TbOF thin-film electroluminescent devices fabricated by radio-frequency magnetron sputtering method

The purpose of this paper is to study the relationship between the oxygen concentration and brightness degradation in ZnS:TbOF green thin-film electroluminescent (EL) devices, The characteristics including crystallinity, optical, and electrical properties were discussed, The brightness-voltage (B-V) measurement results showed that with higher oxygen-content in ZnS:TbOF phosphor layer, lower brightness was measured, It Was consistent with the poor crystallinity, worse photoluminescent intensity, and easier to get moisture in the oxygen-rich (O/Tb > 1) phosphor film, Furthermore, deep level transient spectroscopy (DLTS) measurements identified that when the O/Tb ratio was greater than 1, the oxygen-related deep hole traps E-H1 and/or E-H2 could be detected in the ZnS:TbOF phosphor layer, These E-H1 and/or E-H2 traps were believed to be the main killers for the brightness of the device since they capture most of the holes from the generated electron-hole pairs, This evidence strongly supports that the modified energy transfer model is more dominant than direct impact excitation during the luminescent process.