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1、High-pressure RHEED study of thegrowth of oxide thin films andheterostructures by using PLDJie Li, YF Chen, K Chen, W Peng, P Wang, HFChu, Y Zhang, and Dong Ning Zheng中国科学浣物理研究所 北京凝聚态物理国家实验室INSniUZE or PHYSICS CQHEMADatY Cf SQEZCI5 ： BFIJNG 51OSA4 ； AfiCRATORYMATTER PHYSICSOutlines: Principles of RH
2、EED一 A gate to the atomic-scale control of the surface & interface ；- The state of art film growth with RHEED-PLD systems； What we have done, and what we are doing- In situ RHEED control of the growth of STO, LAO, YBCO, and LCMO epilayers一 Heterostructures ofLCMO /MgO（2）/LCMO（2）/MgO /LCMO /YBCO/LAO一
3、 Other applications SummaryA tomically engineered oxide interface Superconducting Interfaces Between Insulating Oxides (Science 317,1196 (2007) Electric-field control of local ferromagnetism using a magnetoelectric multiferroic (Nature. Mater 7, 478 (2008) High-temperature interface superconductivit
4、y between metallic and insulating copper oxides (Nature 455, 782 (2008) Two-dimensional normal-state quantum oscillations in a superconducting heterostructure (Nature 462, 487 (2009)Multilayers of sharp, cleai; chemically steep, atomically smooth interface with digital layer thickness are essential.
5、Growth modes of thin films step flow一 Good substrate/film lattice match- Wetting- High- Short terrace width Layer-by-layer- Good lattice match- Wetting- Lower Ds一 Longer terrace width Stranski-Krastanov- Monoiayer(s) then 3D- Wetting- Epi-str air一 Island form at ion Volmer-Weber-3D from start一 High
6、surface tensionr no wetting-Rapid roughening“ 一 J -j./一 Coarsening (Oshvald ripanhg)Phil Willmott, Paul Scherrer Institut Zuoz Summer School, August 2008Principles of RHEED0th Laue CircleUsed STO(OOl)Specular SpotShadow Edge、Crystal truncation rods (CTR)Surface Sensitive!V(kV)入（闻10.389100.122200.085
7、3250.0760300.0690500.0525Transmit SpotIntensity oscillation of the specular reflectionOne oscillation period vs.one complete monolayereSu2三ss一工0123Time (s)Layer-by-layer growth modehttp:/lippmaaJssp.u4okyo.ac.jp/rheed/What can RHEED tell us? Pattern一 Streak position (structure)一 Shape of streaks (su
8、rface morphology)- FWHM一 Kikuchi lines Oscillation一 Long time scale (layer- by-layer modulation)一 Short time scale (pulse laser modulation)一 Growth mode transition200010203040Timc(s)o o 00006 4(ndE 一 aacIGrowth mode control: deposition rate vs. temperatureFTG 7 RHEFD 5pnlar spct itre-nity vi fim? me
9、asurpd at variniift。分行可1己 temperatures and lasher repetition rates. All depos.itions were made on the saaie substrate. The surface was allowed to recover at above 1200 C between depositions. The time scales are 5 s at 20 and 10 Hz. 10 s at 5 Hz, 20 s at 2 Hz. 30 s at 1 Hz, 60 s at OJ Hz, and 120 s a
10、t 0.2 Hz.Lippmaa et al., Appl. Phys. Lett-, 76, 2439 (2000)The state of art film growthFigure 6.23 High-angle annular dark field image acquijed by scanning transmission electron microscopy of a LaAlO3/SrliO3 multilayer with various thickneacet of the individual lajera. (a) Overview of the total hete
11、iostiuctuie showing the ceparate LaAlOr (bright) and SrTiO,3 layers. The thicknesGec of the individual layers are indicated in unit cells, (b) Detailed analysis of the LaAlO.j layei with a thickness of only one unit cell.Mark Huijben Interface Engineering for Oxide Electronics: Tuning electronic pro
12、perties by atomically controlled growth , PhD thesis University of Twente, Enschede, The Netherlands (2006). http:/doc.utwente.nl/55832/100sequence 180604020sequence 2vw.g-guBul10080604020一，三星与一SUEI80604020Time isec.Hguie 6.11 KHEED intenB：ty variationc during gror.-th o: a J；LaAlOz/CSrTiO；,)w super
13、latti-oe by puleed laser depceition on a l iOrterminated SrTiOj eu-bstrate. C eaily visible* are the MciJatkins in the RHEED inteneity duriag the first two cequencez recpective ar the top and mi-ddle poBition) and alco during the final sequence fat the bottom).Epitaxial synthesis of Metallic Srn+1Ti
14、nO3n+1Institute of materials research, Tohoku University|RuddlesdenPopp(K (RP) phasc|S5)h ：substh3te 口eaks(sds Msusu-28 (deg)o800100200300400Time (s)SrO STO SrO STO4ML SUC8 ML 511cs10o7000二o o o o 0 o o605 4 3 20=un e) ansuo*-10 2D 304050607020 (deg)Natural superlattice consists of SrTIO, perovikite layr and SrO rocksalt monolayer.Combination of RHEED with PLDMean free path of electrons in nitroger B.L. Thiel et al, Rev. ScL Instrum.77 033705 (2006)4: CCD5: phosphor screen8
