C-axis oriented sol-gel derived LiNb_1-xTa_xO₃ thin films on Si(111) substrates

We have successfully prepared highly c-axis oriented sol-gel derived LiNb_1-xTa_xO₃ films on Si(111) substrates. The orientations of LiNb_1-xTa_xO₃ films for different values of the tantalum composition, x, are investigated. Highly c-axis oriented films were obtained in the composition range of 0<x<0.33 and the degree of the orientation was found to be relatively low when 0.5<x<1. The c-axis orientation of the films is believed to result from a weak effect caused by the 3-fold symmetry match between the film and the Si(111) substrate. C-axis oriented LiNb_1-xTa_xO₃ films are very useful in integrated optical devices, pyroelectric devices, and metal-ferroelectric-semiconductor non-volatile memory applications.