The invention provides a phosphor thin film having a high luminance, a
satisfactory color purity enough to eliminate a need for filters, and a
long luminance life, and best suited for each element of RGB in full color
EL panels. The phosphor thin film of the invention comprises a matrix
material and a luminescent center. The matrix material is an oxysulfide
containing at least an alkaline earth element, Ga and/or In, sulfur (S)
and oxygen (O). In the matrix material, the atomic ratio of oxygen to the
total of oxygen and sulfur, O/(S+O), is from 0.1 to 0.85.
