Growth and Structural Characterization of Sr2TiO4: Chemical Control Over the Terminating SrTiO3 Surface.

Abstract

AbstractThin films of Sr2TiO4 were grown using pulsed laser deposition (PLD) and laser-MBE on [100]-SrTiO3single crystal substrates. Films grown by standard PLD display only a single peak in the X-ray diffraction spectra, corresponding to the (006) peak of the K2NiF4 parent structure. Using a Laser-MBE, controlled two-dimensional growth and RHEED intensity oscillations can be routinely obtained. The period of the RHEED intensity oscillations was confirmed to correspond to the deposition of one-half the unit cell. In contrast to PLD-grown films, the (004) and (006) peaks are observed in XRD spectra for the Laser-MBE-grown films. The intensity of the (004) peak is discussed and modeled with respect to in-plane disorder arising from substrate step-edges and out-of-plane film-substrate structural mismatches. That a single, half unit-cell can be deposited allows one to "flip" the terminating surface of SrTiO3 in a controlled and simple manner from a pure TiO2 layer to a SrO layer. Experimental evidence of the importance of such surface control is given for the SrCuO2 structural stability.