Growth of “colossal” magnetoresistance heterostructures by molecular beam epitaxy

1999 ◽  
Vol 602 ◽  
Author(s):  
J. O'Donnell ◽  
A. E. Andrus ◽  
S. Oh ◽  
E. Colla ◽  
M. Warusawithana ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Colossal Magnetoresistance ◽  
Molecular Beam ◽  
Residual Resistivity ◽  
Bulk Single Crystal ◽  
Heteroepitaxial Growth ◽  
Flat Surfaces ◽  
Narrow Region ◽  
Slight Excess ◽  
Atomically Flat

We discuss the heteroepitaxial growth of La1−xSrxMnO3 films and CaTiO3 insulating barriers by molecular beam epitaxy. We find that the surface morphology and residual resistivity of the manganite electrodes is critically dependent on the film stoichiometry. The most important parameter is the concentration of La+Sr (cubic perovskite A-site cations) to that of Mn (B-site cation). If La+Sr is supplied in slight excess, the films grow with atomically flat surfaces, but the residual resistivity at 4.2K is high (as high as 6500 µΩ-cm), and Curie temperature (Tc) low (<300 K). If Mn is supplied in slight excess, the films have high Tc (370 K) and residual resistivity (35 µΩ-cm) better than bulk single crystal values, but the surface is no longer atomically flat. There appears to be a very narrow region of phase space where it is possible to have low resistivity, high Tc films with atomically flat surfaces. This is precisely where one would like to place heterostructure devices.

Homo- and Hetero-Epitaxial Gallium Nitride Grown by Molecular Beam Epitaxy

1998 ◽  
Vol 537 ◽  
Author(s):  
C.T. Foxon ◽  
T.S. Cheng ◽  
D. Korakakis ◽  
S.V. Novikov ◽  
R.P. Campion ◽  
...  
Keyword(s):  
High Temperature ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
Boundary Structure ◽  
Quantum Well Structures ◽  
Flat Surfaces ◽  
Grain Boundary Structure ◽  
Bulk Gan ◽  
Atomically Flat

AbstractVarious methods have been used to initiate growth by Molecular Beam Epitaxy (MBE) of GaN on sapphire, or other substrates, but there is always a problem with morphology and with a high defect density which results in the formation of a sub-grain boundary structure. We show that by using, homo-epitaxial growth on properly prepared bulk GaN substrates, combined with high temperature growth, we obtain a significant improvement in surface morphology. Growth at sufficiently high temperature leads to a rapid smoothing of the surface and to almost atomically flat surfaces over relatively large areas. Multi-Quantum Well structures grown on such GaN epitaxial films are dislocation free with abrupt interfaces.

scholarly journals Homo- and Hetero-Epitaxial Gallium Nitride Grown by Molecular Beam Epitaxy

1999 ◽  
Vol 4 (S1) ◽  
pp. 484-489 ◽  
Author(s):  
C.T. Foxon ◽  
T.S. Cheng ◽  
D. Korakakis ◽  
S.V. Novikov ◽  
R.P. Campion ◽  
...  
Keyword(s):  
High Temperature ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
Boundary Structure ◽  
Quantum Well Structures ◽  
Flat Surfaces ◽  
Grain Boundary Structure ◽  
Bulk Gan ◽  
Atomically Flat

Various methods have been used to initiate growth by Molecular Beam Epitaxy (MBE) of GaN on sapphire, or other substrates, but there is always a problem with morphology and with a high defect density which results in the formation of a sub-grain boundary structure. We show that by using, homo-epitaxial growth on properly prepared bulk GaN substrates, combined with high temperature growth, we obtain a significant improvement in surface morphology. Growth at sufficiently high temperature leads to a rapid smoothing of the surface and to almost atomically flat surfaces over relatively large areas. Multi-Quantum Well structures grown on such GaN epitaxial films are dislocation free with abrupt interfaces.

The effect of growth condition on the structure of 2H – AlN films deposited on Si(111) by plasma-assisted molecular beam epitaxy

1999 ◽  
Vol 14 (5) ◽  
pp. 2036-2042 ◽  
Author(s):  
U. Kaiser ◽  
P. D. Brown ◽  
I. Khodos ◽  
C. J. Humphreys ◽  
H. P. D. Schenk ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Film Surface ◽  
Interface Structure ◽  
Flat Surfaces ◽  
Si Substrates ◽  
Nitridation Time ◽  
Transmission Electron ◽  
Atomically Flat ◽  
Film Defect

The effects of substrate cleaning, nitridation time, and substrate temperature in the range 800–1000 °C on the microstructure of AlN/Si(111) films grown by simultaneous plasma-assisted molecular beam epitaxy have been investigated. It has been demonstrated, using a combination of conventional and high-resolution transmission electron microscopy, that the interface structure, the film defect structure, and the film surface roughness are strongly related. The formation of single crystal 2H–AlN films with atomically flat surfaces occurs at 800 °C for conditions of 2.5 nm/min growth rate on very pure, atomically flat Si substrates.

Molecular Beam Epitaxy of Single Crystal Colossal Magneto-Resistive Material

1995 ◽  
Vol 401 ◽  
Author(s):  
J. N. Eckstein ◽  
I. Bozovic ◽  
M. Rzchowski ◽  
J. O'donnell ◽  
B. Hinaus ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Atomic Layer ◽  
Growth Conditions ◽  
Dislocation Network ◽  
Layer By Layer ◽  
Flat Surfaces ◽  
Low Field ◽  
Resistive Material ◽  
Atomically Flat

AbstractWe have grown films of (LaSr)MnO3 (LSMO) and (LaCa)MnO3 (LCMO) using atomic layer-by-layer molecular beam epitaxy (ALL-MBE). Depending on growth conditions, substrate lattice constant and the exact cation stoichiometry, the films are either pseudomorphic or strain relaxed. The pseudomorphic films show atomically flat surfaces, with a unit cell terrace structure that is a replica of that observed on the slightly vicinal substrates, while the strain relaxed films show bumpy surfaces correlated with a dislocation network. All films show tetragonal structure and exhibit anisotropic magnetoresistance, with a low field response, (1/R)(dR/dH) as large as 5 T−1.

Heteroepitaxial growth of Ge films on Si substrates by molecular beam epitaxy

1988 ◽  
Vol 53 (22) ◽  
pp. 2179-2181 ◽  
Author(s):  
G. L. Zhou ◽  
K. M. Chen ◽  
W. D. Jiang ◽  
C. Sheng ◽  
X. J. Zhang ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Heteroepitaxial Growth ◽  
Si Substrates

An intermediate (1.0–1.5 monolayers) stage of heteroepitaxial growth of InAs on GaAs(100) during submonolayer molecular beam epitaxy

1996 ◽  
Vol 352-354 ◽  
pp. 646-650 ◽  
Author(s):  
G.M. Guryanov ◽  
G.E. Cirlin ◽  
A.O. Golubok ◽  
S.Ya. Tipissev ◽  
N.N. Ledentsov ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Heteroepitaxial Growth

Influence of Off-Oriented Substrates on Heteroepitaxial Growth of (Ca, Sr)F2 Layers on Si (100)

1989 ◽  
Vol 160 ◽  
Author(s):  
Tetsuroh Minemura ◽  
Junko Asano ◽  
Kazuo Tsutsui ◽  
Seijiro Furukawa
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Epitaxial Layers ◽  
Considerable Influence ◽  
Heteroepitaxial Growth ◽  
Remarkable Effect

AbstractHeteroepitaxial growth of CaxSr1-xF2 layers on Si (100) substrates by molecular beam epitaxy has been investigated for GaAs / fluoride / Si structures. The Si (100) substrates off-oriented toward [011] show no considerable influence on crystallinity of CaF2 and SrF2 epitaxial layers. The off - oriented substrates, however, influence a remarkable effect on CaxSr1-xF2 layers, resulting in poor crystallinity rather than good one. This influence of off-oriented Si (100) substrates on the heteroepitaxy of CaxSr1-xF2 layers was the opposite of that found in GaAs/Si (100) structures.

Heteroepitaxial growth of InSb on (100)GaAs using molecular beam epitaxy

1988 ◽  
Vol 53 (13) ◽  
pp. 1189-1191 ◽  
Author(s):  
G. M. Williams ◽  
C. R. Whitehouse ◽  
C. F. McConville ◽  
A. G. Cullis ◽  
T. Ashley ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Heteroepitaxial Growth
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