Transmission electron microscopy of epitaxial gallium arsenide grown on a variety of silicon substrates by metallorganic chemical vapor deposition

1987 ◽  
Vol 45 ◽  
pp. 342-343
Author(s):  
J. M. Brown ◽  
S. J. Pearton ◽  
R. Caruso ◽  
M. Stavola ◽  
K. T. Short ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Gaas Layer ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
Thermal Expansion Coefficients ◽  
Growth Regime ◽  
Transmission Electron ◽  
Strained Layer Superlattices

The growth of GaAs layers on silicon substrates is under extensive investigation with a view to achieving the integration of GaAs-based optoelectronic devices with Si integrated circuit technology. The large lattice mismatch between Si and GaAs (-4%) together with the differences in the thermal expansion coefficients between the two materials results in a highly stressed interface. Several different approaches have been undertaken in attempts to reduce the dislocation density of the GaAs layer. The inclusion of graded composition GaAsP ‘buffer’ layers, intermediate Ge layers and the inclusion of strained layer superlattices in the growth regime have been reported by many workers. Growth of GaAs directly on Si has been reported to yield GaAs heteroepitaxial films suitable for electronic applications such as FETs and low threshold AlGaAs/GaAs double heterostructure injection lasers.

Antiphase boundaries in β-Sic thin films

1987 ◽  
Vol 45 ◽  
pp. 282-283
Author(s):  
K. L. More ◽  
J. Bentley ◽  
R. F. Davis
Keyword(s):  
Thin Films ◽  
High Speed ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Wide Bandgap ◽  
Silicon Substrates ◽  
State University ◽  
North Carolina State University ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Beta-SiC thin films are currently being grown via chemical vapor deposition (CVD) at North Carolina State University for potential use as a semiconductor material. Silicon carbide is a wide bandgap semiconductor with a high, saturated electron drift velocity and, as such, is a primary candidate material for high-temperature, high-speed, and high-frequency electronic devices. The β-SiC thin films are epitaxially grown on {100} silicon substrates by CVD of silicon and carbon from vapors of SiH4 and C2H4 entrained in H2 at a growth temperature of 1633 K. Since there is a lattice mismatch of -20% and a difference in thermal expansion coefficients of ∼10% between the silicon substrate and β-SiC, the silicon surface is reacted with C2H4 at 1583 K. for 150 s to form a converted β-SiC surface layer, approximately 5 nm thick, which helps prevent the formation of cracks during the growth of the thin films. The films are grown at a rate of ∼2 μm/h and are grown as thick as 40 μm.

Smoothing Effects of MOCVD Grown GaAs/AlxGa1−xAs Superlattices

1991 ◽  
Vol 237 ◽  
Author(s):  
Xian-gang Xu ◽  
Bai-biao Huang ◽  
Shi-wen Liu ◽  
Hong-wen Ren ◽  
Min-hua Jiang
Keyword(s):  
Atmospheric Pressure ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Gaas Layer ◽  
Interface Roughness ◽  
Buffer Layers ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Initial Stage ◽  
Smoothing Effects

ABSTRACTGaAs/AlxGa1-xAs (x=0.5, 0.6, 1.0) superlattices used as buffer layers in HEMT devices have been grown by Metalorganic Chemical Vapor Deposition (MOCVD) at. atmospheric pressure, and characterized by cross-sectional transmission electron microscopy (XTEM). The initial stage of nucleation on the substrates has been clearly verified by examining the undulations of a 30na GaAs layer sandwiched between the substrate and the superlattice. Both Alo.5Gao.5As/GaAs and AlAs/GaAs superlattices can smooth out interface roughness caused by contaminations and dislocations on the substrate surface. The mechanism of smoothing effect has been discussed in detail.

Structural Studies of an InAs-GaAs Superlattice Alloy

1985 ◽  
Vol 47 ◽  
Author(s):  
M. C. Tamargo ◽  
R. Hull ◽  
L. H. Greene ◽  
J. R. Hayes ◽  
N. Tabatabaie ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Layer Structure ◽  
Growth Conditions ◽  
Buffer Layers ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Strained Layer Superlattices ◽  
Lattice Matched

ABSTRACTThin alternating layers of InAs and GaAs have been grown by MBE on buffer layers lattice matched to InP. The layer structure was evaluated by transmission electron microscopy (TEM) and low angle X-ray scattering. Commensurate epitaxial layers approximately 15Å thick were obtained in spite of the large lattice mismatch (7%). These results and their implication for growth conditions of strained-layer superlattices will be discussed.

Bound Exciton Energies, Biaxial Strains, and Defect Microstructures in GaN/AlN/6H-SiC(0001) Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
W. G. Perry ◽  
T. Zheleva ◽  
K. J. Linthicum ◽  
M. D. Bremser ◽  
R. F. Davis ◽  
...  
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Lattice Parameter ◽  
Buffer Layers ◽  
Film Stress ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Defect Microstructures

ABSTRACTBiaxial strains resulting from mismatches in thermal expansion coefficients and lattice parameters in 22 GaN films grown on A1N buffer layers previously deposited on vicinal and on-axis 6H-SiC(0001) substrates were measured via changes in the c-axis lattice parameter (c). Six of the films were in compression, indicating the residual strain due to lattice mismatch was not relieved. A Poisson's ratio of v=0.18 was calculated. The bound exciton energy (EBx) was a linear function of these strains. The shift in EBx with film stress was 23 meV/GPa. The role of the SiC off-axis tilt was investigated for GaN films grown concurrently on the vicinal and on-axis 6H-SiC substrates. Marked variations in EBx and c were observed, with a maximum shift of ΔEBx = 15 meV and Δc = 0.0042 Å. Threading dislocations densities of ~1010/cm2 and ~108/cm2 were determined for GaN films grown on vicinal and on-axis SiC, respectively. A 0.9% residual compressive strain at the GaN/AIN interface was observed by high resolution transmission electron microscopy (HRTEM). It is proposed that the on-axis SiC substrate does not offer a sufficient density of steps for defect formation to relieve the lattice mismatch between GaN and A1N and A1N and SiC.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

Low Pressure MOCVD Growth and Characterization of GaAs and InP on Silicon Substrates

1988 ◽  
Vol 126 ◽  
Author(s):  
M. Razeghi ◽  
M. Defour ◽  
F. Omnes ◽  
J. Nagle ◽  
P. Maurel ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Low Pressure ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
High Quality ◽  
Mocvd Growth ◽  
Vapor Deposition Technique ◽  
Low Pressure Mocvd

ABSTRACTHigh quality GaAs and InP have been grown on silicon substrates, using low pressure metalorganic chemical vapor deposition technique. The growth temperature is 550°C and the growth rate 100 A/min.Photoluminescence, X-ray diffraction and electrochemical profiling verified the high quality of these layers. The use of superlattices as buffer layers, (GaAs/GaInP) in the case of GaAs/Si and (GaInAsP/InP) in the case of InP/Si, decreased the amount of misfit dislocations in the epitaxial layer. Carrier concentrations as low as 5.1015 cm−3 have been measured by electrochemical profiling.

MBE Growth of Low Dislocation and High Mobility GaAs-on-Si

1986 ◽  
Vol 67 ◽  
Author(s):  
Jhang Woo Lee
Keyword(s):  
Layer Structure ◽  
High Mobility ◽  
Gaas Layer ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Molecular Beam Epitaxial ◽  
Transmission Electron ◽  
Low Dislocation Density ◽  
Molecular Beam Epitaxial Growth

ABSTRACTData is presented on the optimization of several molecular beam epitaxial growth processes to provide low dislocation density and high mobility GaAs single crystals on (100) Si wafers. The substrate tilt angle, the growth temperature, and the first buffer layer structure, were investigated Tor this purpose. Using Hall measurements the GaAs layers grown on 2 or 3-degree tilt (100) Si showed consistently high mobilities which are equivalent to the homoepitaxial GaAs mobility. Transmission electron microscopy (TEM) revealed that on tilted (100) Si substrates most of the misfit dislocations were confined within the first 50 Å GaAs layer by forming a type of edge dislocation at the Si surface step edges. Also low temperature grown buffer layers always gave better morphologies and lower etch pit densities while keeping the high mobilities on overgrown GaAs layers.

Growth and Characterizations of Gaas on Inp with Different Buffer Structures by Molecular Beam Epitaxy

1989 ◽  
Vol 148 ◽  
Author(s):  
Xiaoming Liu ◽  
Henry P. Lee ◽  
Shyh Wang ◽  
Thomas George ◽  
Eicke R. Weber ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Gaas Layer ◽  
Optical Quality ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Layer Structures ◽  
Gaas Films ◽  
Initial Deposition ◽  
Strained Layer Superlattices

ABSTRACTWe report the growth and characterizations of 31μm thick GaAs films grown on (100) InP substrates by MBE employing different buffer layer structures during the initial deposition. The buffer layer structures under study are: 1) GaAs layer grown at low temperature; 2) GaAs layer grown at low temperature plus two sets of In0.08Ga0.92As/GaAs strained layer superlattices (SLS) and 3) a transitional compositionally graded InxGal-xAs layer between the InP substrate and the GaAs film. After the buffer layer deposition, the growth was continued by conventionalMBE to a total thickness of 3μm for all samples. From the 77K photoluminescence (PL) measurement, it was found that the sample with SLS layers has the highest PL intensity and the narrowest PL linewidth. Cross-sectional transmission electron microscopy (TEM) studies showed that the SLS is effective in reducing the propagation of threading dislocations and explains the observed superior optical quality from the PL measurement.

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