REU Final Reports 2017 34 to fabricate SrTiO the substrate andsputtering targetduring deposition head andcontrolledan adjustable thedistancebetween this study,In we sputteringcompact used a with gun properties. and structures film thin perovskite control in thisprojectOur goal isto alter growthparameters to film properties. during sputtering deposition are crucial to improve of substrates andgrowthparameter optimization respectively.Selection films, the in strain compressive or tensile in results films the of those than constants instance, For [3]. important selection ofsubstrateslarger with lattice orsmaller are film and between substrate matching orientation and lattice films, thin simplicity ofthesystem [2].Tohigh-quality obtain to due sputtering, magnetron the advantagesof low-cost relative depositionand is films thin stacked The most commontechnique for producing practical performance. device improving and films thin of quality and films interfaces are essentialindetermining the crystalline Highly [1]. circuits capacitors, batteries, and integrated devices, such as multilayer ceramic are heterostructures in thedevelopmentimportant of many film thin Stacked Abstract: Website: http://www.cnf.cornell.edu/cnf_2017reu.html Contact: [email protected], [email protected],[email protected] Primary Source of CNFiREUFunding:NationalScienceFoundation underGrant No.OISE#1559368 CNF iREUMentor:Dr. CNF REU Program: 2017 CornellNanoScaleScience& Technology Facility InternationalResearch ExperienceforUndergraduates Physics, MissouriUniversity ofScienceand Technology Skye Tackkett Growth Parameter Control ofStructures Introduction: (CNF iREU)Program at theNationalInstituteofMaterialScience(NIMS), Tsukuba, Ibaraki, Japan iREU PrincipalInvestigator: Dr. and Properties ofPerovskiteand Properties Thin Films strontiumtantalite aluminum ((LaAlO magnetrongrowth Film sputtering. SrTiO of a study,as this In model comprise.system theywe seek devicesto control the the growth and of a perovskitefilms oxide of film, titanate quality (SrTiO and crystallinity the improve to key is for improving film quality for applications in advanced electronic devices. Lattice engineering of thin films method important an is properties and structures film thin control to parameters growth of Application control, high crystallinity, and smooth surfaces, but deficiency in the films is still an obstacle to obstacle an still improving theelectricalproperties. is films the in deficiency oxygen but surfaces, smooth and crystallinity,high control, Ti and Sr good to leads distance the of alteration that find We target. sputtering and substrates between 3 (STO) thinfilms. Takeo Ohsawa, Electroceramics Group,NationalInstituteforMaterialsScience Naoki Ohashi,Electroceramics Group,NationalInstituteforMaterialsScience 3 ) 0.3 Table 1:Typical depositiongrowth parameters forSTO thinfilms. (Sr 3 wasinvestigated onlattice-matched lanthanumaluminate- 2 AlTaO 6 ) 0.7 resistivity andHall-effect measurements. films the onto using vacuumevaporation to formfor Ohmiccontacts deposited were electrodes titanium Gold/ (XRF). fluorescencex-ray and (XRD), diffraction profilometry,x-rayvia microscopy(AFM), forceatomic characterized were films STO depositions, sputtering the respectively.After mm, 93 and mm, 73 mm, 53 of distance ( a to correspond which mm, 170 or mm, 150 mm, 130 holder the sample heightbut sample, was changedto 1. These conditions werefor heldconstant each Typicalgrowth conditions are summarized in Table nm, 0.387 respectively, and resultingin ( 0.390 are LSAT and STO of constants frequency magnetron sputtering.lattice In-plane LaAlO lattice-matched aluminate, on grown were (LaAlO STO of films Thin Procedure:Experimental ) substrates,) where weon thedistance focused

3 ) 0.3 d (Sr s-t ) between substrate andsputtering target 2 AlTaO 3 LO sbtae uig radio- using substrates (LAO) 6 ) 0.7 10 (ST ad and (LSAT) (100) a STO -a LSAT 3 ), through )/ a LSAT =0.0103. REU Final Reports 2017 35 . Electric properties remained remained . Electric properties s-t We were able to conclude that conclude able to were We grew method sputtering our highly crystalline STO Cation with smooth surfaces. thin films Ti was Sr and for stoichiometry changing the of through controlled d the in deficiency oxygen to due poor films. STO Future Work: necessary is control Oxygen of the properties in improving sputtered thin films. In can next we this control, achieve order to in addition exposure gas use oxygen the sputtering during gas argon to deposition procedure. Additionally, 2000 nm 0.98 Hz AFM scan of 170 mm STO/LSAT of 170 mm STO/LSAT 2000 nm 0.98 Hz AFM scan ×

Kambara, H. et al. Chemical Solution Deposition of Functional Chemical Solution Deposition of Functional H. et al. Kambara, Thin 22: Chapter Springer. Oxide Thin Films. Vienna (Austria): p. 547-570(2013). Capacitors; Film Multilayer (1996). Harp, G.R. et al. Thin Solid Films, 288 (1-2):315-324 Guide. New Hecht,Understanding Lasers: An Entry-Level J. Lasers; 8: Semiconductor Chapter Press. (NY): Wiley-IEEE York p.246-294 (2001). 107(19):192908 (2015). A. et al. AP Letters, Verma, Figure 3: 2000 Figure thin film. I would like to thank my PI, Dr. Naoki Ohashi, my my Naoki Ohashi, PI, Dr. thank my to like I would Lynn Drs. staff, site iREU the Ohsawa, Takeo Dr. mentor, iREU Program. and the CNF and Nancy Healy, Rathbun the National Science by supported was work This OISE: 1559368. Award Foundation References: [1] [2] [3] [4] we can test the effect of changing the angle of the head of changing the angle the effect can test we property for and tune the angle gun our sputtering of of the film growth. control Acknowledgements: . It is clear the -axis parameters -axis parameters s-t c d ) in sample C were were in sample C ) -3 cm 19 -axis oriented and single-phase without and single-phase -axis oriented c reported that compressively strained films STO show that reported a compressively ferroelectric transition [4], our STO films, even sample these effects. C, could not show several orders of magnitude different than the other magnitude different of orders several indicating gray, light samples. In fact,looked C sample an oxygen-deficient film as is usually seen oxide in n-type semiconductors. Although former literatures Electric properties collected from Hall-effect Hall-effect from collected Electric properties measurements showed resistivity carrier concentration (2.8*10 (1.1 Ωcm) and results imply that the enlargement of that the enlargement imply results oxygen and amount of strain compressive from resulted (non)stoichiometry. than cation rather measurement. The XRF analysis of the stoichiometry of the stoichiometry XRF analysis The measurement. revealed a Sr of Sr:Ti ratios in stoichiometric samples B and C. These deficiency in sample A, but near C was very flat. We performed XRF measurements on the STO/LAO samples rather than the LAO STO/LSAT, as does not contain Sr which would convolute the 0.271 nm for samples A and C, The respectively. faint stepped- 3 indicated diagonal lines visible in Figure of sample the surface implying surface, and-terraced The AFM images (Figure 3) of the STO/LSAT samples smooth, more significantly were films thin the revealed with a root-mean-square roughness of 0.177 nm and oscillations visible on the 200 peak are by confirmed an was which crystalline, indication highly are films the 0.1°. peak widths around scans showing curve rocking dashed line in Figure 2. The lower peak angles indicate indicate peak angles 2. The lower Figure line in dashed the films are compressively to led which STO, of that than lower is strained, LSAT of constant as the lattice the lengthening of the c-axis parameters. Additionally, impurity peaks. A closer look at the 200 films peak of shows the all three film the by peak, represented than the bulk STO angles peaks occurred at lower Figure Figure 1 shows XRD under different samples deposited wide scans of the films were STO/LSAT Results and Conclusions: Results Figure 1, left: XRD wide scan of STO/LSAT samples. Figure 2, right: XRD (200) peak of Figure samples. of STO/LSAT 1, left: XRD wide scan Figure samples. STO/LSAT