Orientation of MgO thin films grown by pulsed laser deposition

Pulsed laser deposition technique has been employed to grow MgO thin films with preferred orientation on Si(1 0 0) and SiO2/Si(1 0 0) substrates. The orientation of MgO thin films has been investigated in detail by varying deposition parameters. XRD analyses showed that the preferred orientation of MgO thin films changed from (1 1 1) to (1 0 0) as laser fluence decreased and oxygen pressure increased to some extent. Substrate temperature seemed to have little influence on the orientation of MgO thin films deposited at high laser fluences. TEM images of the (1 0 0)-oriented MgO thin films on Si(1 0 0) deposited at 400 °C and the laser fluence of 3 J/cm2 in the oxygen pressure of 200 mTorr demonstrated that there existed a thin amorphous oxide layer of about 2 nm at MgO/Si interfaces due to the oxidation of the Si surface by the residual oxygen. MgO films with controlled orientations are suitable as a buffer layer for the growth of high-quality ferroelectric and superconducting overlayers.