Development of high dielectric constant epitaxial oxides on silicon by molecular beam epitaxy

Thin films of perovskite-type oxide SrTiO3 have been grown epitaxially on Si(001) substrates using molecular beam epitaxy. Using reflection high energy electron diffraction (RHEED) we have determined the optimum growth conditions for these type of oxides directly on silicon. Also, observations of RHEED during growth and X-ray diffraction (XRD) analysis indicate that high quality heteroepitaxy on Si takes place with SrTiO3(001)//Si(001) and SrTiO3[010]//Si[110]. Thin SrTiO3 layers grown directly on Si were used as the gate dielectric for the fabrication of MOSFET devices. An effective oxide thickness <10 Å has been obtained for a 110 Å thick SrTiO3 dielectric film with interface state density around 6.4×1010 cm−2 eV−1, and the inversion layer carrier mobilities of 220 and 62 cm2 V−1 s−1 for NMOS and PMOS devices, respectively.