Growth of La1−xSrxFeO3 thin films by atomic layer deposition

Abstract

Thin films of La_1−xSr_xFeO₃ have been prepared by the ALD (atomic layer deposition) technique using La(thd)₃ (Hthd = 2,2,6,6-tetramethylheptane-3,5-dione), Sr(thd)₂, Fe(thd)₃, and ozone as precursors. A so-called ALD window is found in the temperature range 200 to 360 °C for LaFeO₃. The effect of the pulsing procedure for the precursors on the composition of the films is examined. The results are discussed in relation to a model which ascribes differences between pulsed and obtained stoichiometries to individually different surface-area demands of the precursors. The La_1−xSr_xFeO₃ films turned out to contain only small amounts of carbonate impurities despite the fact that films prepared from Sr(thd)₂ and ozone under the same conditions contains virtually pure SrCO₃. Films of La_1−xSr_xFeO₃ have been deposited on substrates of (amorphous) soda-lime glass and single crystals of Si(100), SrTiO₃(100), and LaAlO₃(012). Annealed films on soda-lime glass and Si(100) substrates turned out to be polycrystalline with virtually random orientation of the crystallites. Those on MgO(100) and SrTiO₃(100) substrates showed some degree of crystal orientation, whereas the annealed films on LaAlO₃(012) proved to contain distinctly oriented crystallites with mosaic features.