SYNTHESIS OF ALN BY REACTIVE SPUTTERING

We present a systematic study of the sub-band gap optical absorption c oefficients alpha(h nu) in the range 1.2-6 eV vs. deposition-temperatu re (T-s from 77 to 450 degrees C) films deposited on silica by 13.6 MH z magnetron sputtering of an Al target with 53 and 72% N-2 in the reac tive mixture. X-ray diffraction, infrared absorption and Raman diffusi on are also presented, mainly on films deposited on Si in the same ran to help in the characterisation of the films. All signals are specifi c of AlN polycrystalline films, which are of better quality when depos ited with 72% N-2. The lowest sub-band gap optical absorption around 5 x 10(2) cm(-1) is obtained fur deposition on silica at T-s = 300 degr ees C with 72% N-2 and is close to that of heteroepitaxial films depos ited on sapphire. (C) 1997 Elsevier Science S.A.