Real-Time Monitoring by Spectroscopic Ellipsometry and Desorption Mass Spectroscopy During Molecular Beam Epitaxy of AlGaAs/GaAs at High Substrate Temperatures

1999 ◽  
Vol 569 ◽  
Author(s):  
W. T. Taferner ◽  
K. Mahalingam ◽  
D. L. Dorsey ◽  
K. G. Eyink
Keyword(s):  
Molecular Beam Epitaxy ◽  
Mass Spectroscopy ◽  
Spectroscopic Ellipsometry ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Gaas Layer ◽  
Ex Situ ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Substrate Temperatures

ABSTRACTA series of AlGaAs/GaAs depositions were monitored in-situ by spectroscopic ellipsometry and desorption mass spectroscopy, under various substrate temperatures (890 K - 990 K) where non-unity sticking conditions occur. An upper bound on the temperature where AlGaAs/GaAs heterostructures may be grown was determined. Ex-situ cross-sectional transmission electron microscopy verified that the AlGaAs/GaAs layer thicknesses grown by molecular beam epitaxy were accurately determined by spectroscopic ellipsometry at these elevated temperatures. The substrate temperature dependence on Ga desorption rates was consistent with Monte Carlo simulation where desorption from both physisorbed and chemisorbed states were included.

Optimization of synthesis of the solid solution, Pb(Zr1–xTix)O3 on a single substrate using a high-throughput modified molecular-beam epitaxy technique

2009 ◽  
Vol 24 (1) ◽  
pp. 164-172 ◽  
Author(s):  
P.S. Anderson ◽  
S. Guerin ◽  
B.E. Hayden ◽  
Y. Han ◽  
M. Pasha ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
High Throughput ◽  
Molecular Beam ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Single Substrate ◽  
Transmission Electron ◽  
Substrate Temperatures

Synthesis of Pb(Zr1–xTix)O3 (PZT) on a single substrate using a high-throughput molecular-beam epitaxy technique was demonstrated. In situ synthesis of crystalline PZT at elevated substrate temperatures could not be achieved, as reevaporation of Pb (PbO) occurred and the partial pressure of O2 was insufficient to prevent formation of a PbPtx phase during deposition. Instead, ex situ postdeposition annealing was performed on PZT deposited at room temperature. Dense single phase PZT was prepared with a compositional range of 0.1 > x > 0.9, for film thicknesses up to 800 nm. Transmission electron microscopy revealed the grain size increased from 50 nm to ∼0.5 μm with increasing Zr-concentration and became more columnar. Raman, x-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy results revealed a morphotropic phase boundary between rhombohedral and tetragonal phases occurred at x ∼0.4 rather than at x = 0.47 in bulk ceramics. This was attributed to clamping arising from mismatch in thermal expansion between the film and substrate.

Tem Investigations of CdTe/GaAs(001) Interfaces

1993 ◽  
Vol 319 ◽  
Author(s):  
J.E. Angelo ◽  
W.W. Gerberich ◽  
G. Bratina ◽  
L. Sorba ◽  
A. Franciosi ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Defect Structure ◽  
Molecular Beam ◽  
Misfit Strain ◽  
Growth Direction ◽  
Film Structure ◽  
Buffer Layers ◽  
Ex Situ ◽  
Cross Sectional ◽  
Transmission Electron

AbstractIn this study, cross-sectional transmission electron microscopy (XTEM) was used to investigate the defect structure at the interface between CdTe(001) and GaAs(001) as well as CdTe(1 11) and GaAs(001). The heterostructures were fabricated by molecular beam epitaxy on GaAs(001) buffer layers grown in-situ by molecular beam epitaxy. The defect structure at the as-deposited CdTe(001)/GaAs(001) interface consists of both dislocations and planar faults. The planar faults are both microtwins and stacking faults. It is found that annealing of the film ex-situ causes a restructuring of the CdTe near the interface, with the microtwins being completely removed upon annealing to 450°C for 100 hours. The CdTe(111)/GaAs(001) thin film structure consists of a large number of microtwins parallel to the growth direction. This twinned structure is shown to be related to the relaxation of a residual misfit strain normal to the twin direction. Possible mechanisms for the relaxation are discussed.

Investigation of crystal properties of TmP/GaAs and GaAs/TmP/GaAs heterostructures grown by molecular beam epitaxy

2001 ◽  
Vol 16 (11) ◽  
pp. 3266-3273 ◽  
Author(s):  
C. H. Lin ◽  
R. J. Hwu ◽  
L. P. Sadwick
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Gaas Layer ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Crystal Properties ◽  
Device Applications ◽  
Composition Profiles

Single-crystal thulium phosphide (TmP) was grown heteroepitaxially on (001) GaAs substrates by molecular beam epitaxy with the orientation relationship [100]TmP//[100]GaAs and {001}TmP//{001}GaAs. The crystal properties and the defects in TmP/GaAs, GaAs/TmP/GaAs heterostructure were characterized through x-ray diffraction, atomic force microscopy, and transmission electron microscopy. TmP was found to have a huge difference in thermal expansion coefficient compared GaAs, which produced high tensile residual stress and may result in the formation of defects. The major defects in the top GaAs layer are stacking faults or microtwins, and they directly correlated with the islandlike surface morphology of the GaAs overlayer. The composition profiles of the TmP/GaAs heterostructure were measured by secondary ion mass spectrometry. The reason for surface segregation of Tm and Ga atoms is discussed and is primarily due to their higher diffusion coefficient near the surface as compared to that in the TmP epilayer bulk. The thermally stable characters of the TmP/GaAs heterostructures allow them to be promising candidates in various device applications.

Defects in Mbe-Grown GaAs/ScxEr1–xAs/GaAs Layers

1990 ◽  
Vol 198 ◽  
Author(s):  
Jane G. Zhu ◽  
Chris J. Palmstrdøm ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Growth Stage ◽  
Molecular Beam ◽  
Gaas Layer ◽  
Stacking Fault ◽  
Initial Growth ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTThe microstructure and the structure of defects in GaAs/ScxEr1–xAs/GaAs (x=0 and 0.3) heterostructures grown on (100) GaAs substrates by molecular beam epitaxy have been characterized using transmission electron microscopy. The top GaAs layer forms islands on ScxEr1–xAs at the initial growth stage, and the area covered by GaAs varies with the growth temperature. In addition to regions of epitactic (100) GaAs, regions of {122}- and (111)-oriented GaAs are observed on (100)-oriented ScxEr1–xAs. A high density of stacking-fault pyramids is found in epilayers of GaAs grown on a thin epilayer of ErAs, where the ErAs layers are only one or two monolayers thick. The apex of each stacking-fault pyramid is located at the ScxEr1–xAs/GaAs interface.

Growth and characterization of GaAs on Si substrates grown by molecular-beam epitaxy

1987 ◽  
Vol 65 (8) ◽  
pp. 897-903
Author(s):  
P. Mandeville ◽  
A. J. SpringThorpe ◽  
C. J. Miner ◽  
R. A. Bruce ◽  
J. F. Currie ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
Growth Parameters ◽  
Current Gain ◽  
Hall Resistance ◽  
Cross Sectional ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas

Single-crystal GaAs layers have been grown by molecular beam epitaxy (MBE) on (100) Si substrates. Surface morphology, defect density, and optical and electrical properties have been studied as a function of the growth parameters. The characterization techniques included photoluminescence, Hall effect, cross-sectional transmission electron microscopy, and X-ray diffraction. GaAs metal semiconductor field-effect transitors on Si exhibited transconductances of 128 mS∙mm−1 and current-gain cutoff frequencies as high as 19 GHz. Special heterostructures showed Shubnikov–de Haas oscillations at low temperature and plateaux in the Hall resistance, which confirmed the presence of two-dimensional electron gas in the heterostructure.

Study on Barium Strontium Titanate Thin Films Integrated on Si Substrates by Laser Molecular Beam Epitaxy

2009 ◽  
Vol 79-82 ◽  
pp. 823-826
Author(s):  
X.Y. Zhou ◽  
Yun Zhou ◽  
G.Y. Wang ◽  
Y. Wang ◽  
Helen Lai Wah Chan ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Structure ◽  
Bias Field ◽  
Sio2 Layer ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Laser Molecular Beam Epitaxy ◽  
Si Substrates ◽  
Transmission Electron

(Ba,Sr)TiO3 thin film has been deposited on Si (001) wafer with the SiO2 layer as the block layer through laser molecular-beam epitaxy using an ultra thin Sr layer as template. X-ray diffraction measurements and the cross-sectional observations under transmission electron microscope indicated that BST was well crystallized. This deposition of Sr layer is considered to remove the thin SiO2 layer to produce a layer, which is crystallized and has a lattice structure matching with that of perovskite BST. The maximum in-plane dielectric tunability is calculated to be 50% at 1 GHz under a moderate DC bias field of 13.3 V/µm. This BST/Si structure is believed to be a promising candidate in the development of ferroelectric BST-based microwave devices.

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