An electro-luminescent material and solid state electro-luminescent device comprising a mixed material layer formed of a mixture of silicon and silicon oxide doped with rare earth ions so as to show intense room-temperature photo-and electro-luminescence is described. The luminescence is due to internal transitions of the rare earth ions. The mixed material layer has an oxygen content ranging from 1 to 65 atomic% and is produced by vapor deposition and rare earth ions implant. A separated implant with elements of the V or III column of the periodic table of elements gives rise to a PN junction. The so obtained structure is then subjected to thermal treatment in the range 400-1100 C.