Atomic layer deposited lanthanum-metal oxide dielectric layers and methods of fabricating such dielectric layers provide an insulating layer in a variety of structures for use in a wide range of electronic devices. In an embodiment, a lanthanum aluminum oxide dielectric layer is formed by depositing aluminum and lanthanum by atomic layer deposition onto a substrate surface in which precursors to deposit the lanthanum include a trisethylcyclopentadionatolanthanum precursor and/or a trisdipyvaloylmethanatolanthanum precursor.