Conductive Oxide Srruo <sub> 3 </ Sub> Thin Film Growth And Ferroelectric Integration

Ferroelectric thin films have been used in a lot of devices due to their important characteristics. The electrode of ferroelectric thin film devices mostly use precious metals such as Pt. Epitaxial ferroelectric thin film can not be obtained on metal electrode because of lattice mismatch. Besides, metal electrode have many other disadvantages. Conductive metallic oxide SrRuO₃(SRO) have received continuous attention due to its interesting electrical and magnetic properties. SRO is an ideal bottom electrode in devices incorporating oriented ferroelectric films due to its outstanding thermal conductivity and stability, high resistance to chemical erosion, and good compatibility in structure with perovskite type ferroelectric materials. In this paper, the growth of SRO thin films on different substrates and the integration of ferroelectric thin films with SRO electrodes have been systematically studied.Firstly, SRO films were deposited on SrTiO₃ (STO),LaAlO₃(LAO),MgO substrates by pulse laser deposition(PLD). The effect of growth temperature,oxygen pressure and pulse laser energy intensity on crystal structure,surface morphology,electrical resistivity of SRO thin films were studied. SRO thin films grow epitaxially on MgO substrate exhibiting two out-of-plane orientations,[110]SRO//[100]MgO and 45°-rotated cube-on-cube [001]SRO//[100]MgO, which are formed by two in-plane arrangements each. The epitaxial SRO thin films on MgO substrate were highly conductive, making these materials excellent candidates for use as thin-film electrodes.Then, ferroelectric BTO thin films were deposited on SRO/STO and SRO/MgO electrodes by PLD. When grown on SRO/STO, BTO films were preferentially c-axis oriented. Using MgO as a substrate,produced a mixture of a-axis and c-axis oriented grains of BTO. The PFM analysis and P-E tests indicated that epitaxial BTO films with c-axis orientation on STO substrate exhibited stronger ferroelectricity as compared to the MgO one. Epitaxial BST films were fabricated on SRO/MgO by sputtering. Using the SRO films deposited at a temperature of 700℃as electrode, the BST films exhibited a dielectric constant and loss tangent measured at 100KHz and 300K of 270 and 5%,respectively. Finally, SRO thin films were deposited on Pt/Ti/SiO₂/Si substrates. The effect of growth temperature and pulse laser energy on crystal structure and surface morphology of SRO thin films were studied. It was found that amorphous films were obtained when the pulse laser energy intensity was lower than 130mj/pulse while crystalline films were obtained when the pulse laser energy intensity was higher than 130mj/pulse. BST films fabricated on SRO/Pt composite electrode by sputtering were polycrystalline, exhibiting a dielectric constant and loss tangent measured at 100KHz and 300K of 1030 and 3%, respectively.