PHOTOLUMINESCENCE OF ND-DOPED LINBO3 FILMS PREPARED BY PULSED-LASER DEPOSITION

Nd-doped LiNbO3 films have been prepared on (012) sapphire substrates by pulsed laser deposition. LiNbO3 phase is formed using Li rich targe ts, a 1.5x10(-2) mbar oxygen pressure atmosphere, and heating the subs trate to 520 degrees C. The crystallinity of 1-mu m-thick films has be en enhanced by postdeposition thermal treatments at 600 degrees C. The [Nd]/[Nb] concentration ratio in the film is equal to its value in th e target; however, a limit for the Nd incorporation to the LiNbO3 phas e has been found due to the preferential nucleation of Li deficient ph ases for [Nd]/[Nb]>0.1. The Nd photoluminescence of the films have bee n studied at 77 K exciting the F-4(3/2) multiplet. The photoluminescen ce of congruent LiNbO, single crystals is well reproduced in films pre pared from targets with a [Li]/[Nb]=1.6 composition. Films prepared fr om targets with a [Li]/[Nb]=3 composition, additionally show an emissi on, with a main maximum at 1064 nm, the splitting of the F-4(3/2) mult iplet being 80 cm(-1). The possible origin of the latter photoluminesc ence is discussed. (C) 1997 American Institute of Physics.