Epitaxial integration of photoresponsive Bi0.4Ca0.6MnO3 with Si(001)

Abstract

Previously it has been shown that the resistivity of Bi0.4Ca0.6MnO3 epitaxial thin films on oxide substrates decreases significantly upon illumination with visible light. The resistivity decrease is observed over a wide temperature range and is understood as arising due to the destruction of charge ordering. The light responsivity makes Bi0.4Ca0.6MnO3 thin films attractive for photonic and optoelectronic device applications. In this paper, we report the heteroepitaxy of Bi0.4Ca0.6MnO3 thin films on (001) Si which is relevant for the potential integration of the optoelectronic/photonic functionality of Bi0.4Ca0.6MnO3 with semiconductor electronics. As in the case of other perovskite oxides, heteroepitaxy of Bi0.4Ca0.6MnO3 on Si requires the use of buffer layers to circumvent the problems associated with the presence of an amorphous native silicon dioxide layer and the reactivity of perovskite oxides with Si at high temperatures. We demonstrate that high quality epitaxial thin films of Bi0.4Ca0.6MnO3 can be grown via pulse laser deposition on Si that has been prebuffered with a SrTiO3 layer via a Motorola molecular beam epitaxy process. The magnitude and dynamics of the photoresponse in these films is comparable to that of Bi0.4Ca0.6MnO3 films on oxide substrates.