We have proposed ReMnO3 (Re: rare earth) thin films for nonvolatile memory devices. We examine the growth mechanism of YMnO3 films on (0001)ZnO:Al/(0001) sapphire substrate using rf magnetron sputtering and pulsed laser deposition methods with oxide compound target. We have succeeded in obtaining (0001) epitaxial YMnO3 films on (111) MgO and (0001)ZnO:Al/(0001) sapphire substrate, and polycrystalline films on (111)Pt/(111)MgO. For an optimal structure, the film needed much less oxygen from the gas phase compared to other oxide films. The composition (Y/Mn ratio) of the YMnO3 films changed drastically by varying the partial oxygen pressure in the sputtering gas. In addition the Y/Mn ratio slinfled with sputter time due to target surface modification, probably caused by Y segregation. An extremely small amount of oxygen is required to form the YMnO3 crystal. This was confirmed by pulsed laser deposition experiments.

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We have proposed ReMnO3 (Re: Rare earth elements) films for metal-ferroelectric-semiconductor field effect transistor-(MFSFET) type ferroelectric random access memories (Ferroelectric RAMs). For this kind of application, since ReMnO3 films must be fabricated directly on Si substrates, this wrote focuses on the fabrication of YMnO3 films on Si substrates with and without buffer layers. Although only amorphous YMnO3 films are obtained without buffer layers, crystalline films are obtained using Y–Mn–O buffer layers deposited without introducing oxygen. YMnO3 films can be epitaxially grown on the top of epitaxial Y2O3 on (111)Si. For both crystalline YMnO3 films, although hysteresis behavior in D-E measurement is observed, remanent polarizations are quite small. The role of buffer layers on the thin film growth of YMnO3 on (111)Si is discussed.

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