Intense red catho- and photoluminescence from 200 nm thick samarium doped amorphous AlN thin films

Samarium (Sm) doped aluminum nitride (AlN) thin films are deposited on silicon (100) substrates at 77 K by rf magnetron sputtering method. Thick films of 200 nm are grown at 100-200 watts RF power and 5-8 m Torr nitrogen, using a metal target of Al with Sm. X-ray diffraction results show that films are amorphous. Cathodoluminescence (CL) studies are performed and four peaks are observed in Sm at 564, 600, 648, and 707 nm as a result of ⁴G _5/2 → ⁶H _5/2, ⁴G _5/2 → ⁶H _7/2, ⁴G _5/2 → ⁶H _9/2, and ⁴G _5/2 → ⁶H _11/2 transitions. Photoluminescence (PL) provides dominant peaks at 600 and 707 nm while CL gives the intense peaks at 600 nm and 648 nm, respectively. Films are thermally activated at 1,200 K for half an hour in a nitrogen atmosphere. Thermal activation enhances the intensity of luminescence.