Adsorption-Controlled Growth of Ferroelectric PbTiO, and Bi4Ti3O12 Films for Nonvolatile Memory Applications by MBE

1997 ◽  
Vol 474 ◽  
Author(s):  
C. D. Theis ◽  
J. Yeh ◽  
M. E. Hawley ◽  
G. W. Brown ◽  
D. G. Schlom

ABSTRACTEpitaxial PbTiO3 and Bi4Ti3O12 thin films have been grown on (100) SrTiO3 and (100) LaAlO3 substrates by reactive molecular beam epitaxy (MBE). Titanium is supplied to the film in the form of shuttered bursts each containing a one monolayer dose of titanium atoms for the growth of PbTi03 and three monolayers for the growth of Bi4Ti3O12. Lead, bismuth, and ozone are continuously supplied to the surface of the depositing film. Growth of phase pure, c-axis oriented epitaxial films with bulk lattice constants is achieved using an overpressure of these volatile species. With the proper choice of substrate temperature (600 – 650 °C) and ozone background pressure (PO3 = 2×10−5 Torr), the excess of the volatile metals and ozone desorb from the surface of the depositing film leaving a phase-pure stoichiometric crystal. The smooth PbTiO3 surface morphology revealed by atomic force microscopy (AFM) suggests that the PbTiO3 films grow in a layer-by-layer fashion. In contrast the Bi4Ti3O12 films contain islands which evolve either continuously or around screw dislocations via a spiral-type growth mechanism.

2021 ◽  
Vol 91 (6) ◽  
pp. 1038
Author(s):  
Д.В. Ищенко ◽  
А.Н. Акимов ◽  
И.О. Ахундов ◽  
В.А. Голяшов ◽  
А.Э. Климов ◽  
...  

The topology of the surface of epitaxial films of lead tin telluride solid solution, including those with the addition of indium (Pb1-xSnxTe:In), grown on single-crystal BaF2 (111) substrates and a CaF2/BaF2 buffer layer on Si (111) was studied by atomic force microscopy. It is shown that the characteristic statistical indicators of the relief are due to the peculiarities of film growth and the mechanism of incorporation of Indians, the excess content of which was registered on the surface ex situ by X-ray photoelectron spectroscopy.


1995 ◽  
Vol 401 ◽  
Author(s):  
Y. Gao ◽  
S. A. Chambers

AbstractEpitaxial films of NbxTi1−xO2 rutile were grown on TiO2 (110) and (100) at 600 °C by oxygen-plasma-assisted molecular beam epitaxy using elemental Ti and Nb sources. The epitaxial films were characterized by means of reflection high-energy and low-energy electron diffraction (RHEED/LEED), x-ray photoelectron spectroscopy and diffraction (XPS/XPD), ultraviolet photoemission spectroscopy (UPS) and atomic force microscopy (AFM). The epitaxial films grow in a layer-by-layer fashion and have excellent short- and long-range structure order at x≤0.3 on TiO2(110) and at x≤0.15 on TiO2(100). However, the epitaxial films become rough and disorder at higher doping levels. Nb substitutionally incorporates at cation lattice sites, leading to NbxTi1−xO2 solid solutions. In addition, the oxidation state of Nb in the NbxTi1−xO2 films has been determined to be +4.


1995 ◽  
Vol 388 ◽  
Author(s):  
Gun Yong Sung ◽  
Jeong Dae Suh ◽  
Sang-Don Jung

AbstractThe initial stages of the growth of b-axis oriented PrBa2Cu3O7-x (PBCO) films on LaSrGaO4 (100) substrates were investigated by atomic force microscopy to follow the growth of the thin films. Series of films with thickness ranging between 0.34 nm and 100 nm were prepared under identical pulsed laser deposition conditions. No sprial-topped or flat-topped islands were observed and the scale of the surface roughness was lower than that of the c-axis oriented growth mode. the 300 nm-thick in-plane aligned a-axis oriented YBCO films have the root mean square (RMS) surface roughness of 2 nm. It is considered that the b-axis oriented PBCO films on LaSrGaO4 (100) substrates were nucleated and grown by layer-by-layer like growth mode.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Marcio N. Gomes ◽  
Jackeline B. Brito ◽  
Josmary R. Silva ◽  
Nara C. de Souza

We report on the preparation and study of layer-by-layer films of wine alternated with bovine serum albumin (BSA). We found that the exponential and/or linear growth of the films is dependent on the deposition time. Atomic force microscopy images were analysed using scale laws and the fractal dimension, and the results suggested that the BSA/wine film growth regime is determined by sub-bilayer or bilayer growth. Exponential growth was associated with a sub-bilayer deposition regime, whereas linear growth was associated with a bilayer deposition in which a constant amount of material is deposited.


1995 ◽  
Vol 401 ◽  
Author(s):  
Kiyotaka Wasa ◽  
Toshifumi Sato ◽  
Hideaki Adachi ◽  
Kentaro Setsune ◽  
S. Trolier-McKinstry ◽  
...  

AbstractThin films of perovskite Pb–Ti–O3 families were heteroepitaxially grown by sputtering on (0001)sapphire and/or (001)SrTiO (ST). These epitaxial films contained microstructures, although X–ray diffraction analysis suggested formation of single crystal phase with three dimentional crystal orientation. Their microstructures were studied by the electron microscopy, atomic force microscopy, and spectroscopic ellipsometry so as to find factors which influence the formation of the microstructure. It was found that the orientation of the substrate surface and the chemical composition of adatoms during initial film growth strongly affected the formation of the microstructures. Sputtered PbTiO3 (PT) thin films under a stoichiometric condition on a miscut(001) ST(miscut 1.7 degree) realized the growth of continuous single crystal thin films of 10–100nm thick with extremely smooth surface with surface roughness less than 3nm. Deposition on a miscut substrate under a stoichiometric condition is essential to make continuous thin films of perovskite of single crystal phase.


2001 ◽  
Vol 673 ◽  
Author(s):  
A. Maxwell Andrews ◽  
J.S. Speck ◽  
A.E. Romanov ◽  
M. Bobeth ◽  
W. Pompe

ABSTRACTAn approach is developed for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth. It is demonstrated that both strain relaxation associated with misfit dislocation formation and subsequent step elimination (e.g. by step-flow growth) are responsible for the appearance of nanoscopic surface height undulations (0.1-10 nm) on a mesoscopic (∼100 nm) lateral scale. The results of Monte Carlo simulations for dislocation- assisted strain relaxation and subsequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ∼50 Å in an approximately 70% strain relaxed In0.25Ga0.75As layers. The model is supported by atomic force microscopy (AFM) observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation generation.


2005 ◽  
Vol 202 (1) ◽  
pp. 3-3 ◽  
Author(s):  
Wei Chen ◽  
Kian Ping Loh ◽  
Ming Lin ◽  
Rong Liu ◽  
Andrew T. S. Wee

2009 ◽  
Vol 13 (07) ◽  
pp. 774-778 ◽  
Author(s):  
Byung-Soon Kim ◽  
Young-A Son

In this study, self-assembled alternating film using poly(diallyldimethylammonium chloride) (PDDAC) and meso-tetrakis(4-carboxyphenyl)porphyrin (MTCP) was prepared as a multilayer deposition on glass substrate. This preparation technique for dye deposition may provide new feasibilities to achieve the manufacture of ultrathin films for nanotechnology application. The deposition films were characterized by UV-vis spectrophotometer and Atomic Force Microscopy (AFM) analysis. The results of UV-vis spectra showed that the absorbance characteristic of the multilayer films linearly increased with an increased number of PDDAC and MTCP bilayers. AFM analysis showed the film surface was relatively uniform and the progressive growth of layers was determined.


1998 ◽  
Vol 15 (11) ◽  
pp. 822-824 ◽  
Author(s):  
Jian-long Li ◽  
Ge Meng ◽  
Ke-hui Wu ◽  
En-ge Wang

2008 ◽  
Vol 1143 ◽  
Author(s):  
Bijandra Kumar ◽  
Mickaël Castro ◽  
Jianbo Lu ◽  
Jean-François Feller

ABSTRACTOrganic vapour sensors based on poly (methylmethacrylate)-multi-wall carbon nanotubes (PMMA-CNT) conductive polymer nanocomposite (CPC) were developed via layer by layer technique by spray deposition. CPC Sensors were exposed to three different classes of solvents (chloroform, methanol and water) and their chemo-electrical properties were followed as a function of CNTcontent in dynamic mode. Detection time was found to be shorter than that necessary for full recovery of initial state. CNT real three dimensional network has been visualized by Atomic force microscopy in a field assisted intermittent contact mode. More interestingly real conductive network system and electrical ability of CPC have been explored by current-sensing atomic force microscopy (CS-AFM). Realistic effect of voltage on electrical conductivity has been found linear.


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