Atomic Layer Deposition of Hexagonal and Orthorhombic YMnO3 Thin Films

Thin films of both the hexagonal and orthorhombic forms of YMnO3 have been fabricated through atomic layer deposition (ALD) and subsequent heat treatment. ALD-type growth of essentially cation-stoichiometric YMnO3 films was achieved in a reproducible manner in a temperature interval of 250-300 degrees C using Y(thd)(3), Mn(thd)(3), and ozone as precursors. The as-deposited films were amorphous, but a postdeposition heat treatment carried out in a temperature range of 750-900 degrees C depending on the substrate/polymorph yielded highly crystalline films. On Si(100) substrate, the product was the hexagonal phase of YMnO3, whereas on LaAlO3(100) and SrTiO3(100) substrates, the metastable orthorhombic YMnO3 phase was formed. On the perovskite substrates, the films were highly oriented, the direction of the orientation moreover depending oil the choice of the substrate crystal.