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.

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.

X-Ray Strain Measurements in IV-VI Semiconductor Super-Lattices at Low Temperature

1983 ◽  
Vol 27 ◽  
pp. 171-178 ◽  
Author(s):  
E.J. Fantner ◽  
H. Clemens ◽  
G. Bauer
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Tensile Strain ◽  
Room Temperature ◽  
Lattice Mismatch ◽  
Misfit Strain ◽  
Strain Measurements ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

AbstractMultilayers composed of many thin films of PbTe and Pb1-xSnxTe on BaF2 substrates were grown epitaxially by hot-wall-vapor deposition. In order to investigate the fraction of the total misfit (2.5x10-3 at x=O, 12) accommodated by misfit strain we have performed strain measurements on these superlattices by two different X-ray diffractometer techniques. We also report on substrate induced strain due to different thermal expansion coefficients of films and substrate. For film thicknesses smaller than 300 nm there is clear evidence for almost complete accommodation of lattice mismatch by misfit strain. Below room temperature the substrate induces a tensile strain which is comparable to that of the misfit strain.

TEM characterization of III-V semiconductors heteroepitaxially grown on Si substrates

1989 ◽  
Vol 47 ◽  
pp. 688-689
Author(s):  
K.M. Jones ◽  
M.M. Al-Jassim
Keyword(s):  
Lattice Mismatch ◽  
Ion Beam ◽  
Liquid Nitrogen Temperature ◽  
Beam Current ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Beam Voltage ◽  
High Resolution Tem ◽  
Expansion Coefficients

There has been considerable improvement over the last two years in the growth of III-V semiconductors on Si substrates, and some majority carrier devices such as FETs were reported using this technology. However, there are still a number of formidable problems to overcome in order to obtain high quality layers for minority carrier devices. Not excluding serious problems such as the large difference in thermal expansion coefficients, the effects of interface contamination and lattice mismatch were recognized by many workers to be the most adverse. In this work, these effects were investigated using conventional, analytical and high resolution TEM in an attempt to produce better quality epilayers. All layers were grown by MOCVD on (100) Si substrates misoriented by 2° towards (110). The TEM foils were prepared by a combination of mechanical polishing and I/Ar ion beam milling. This mixture of iodine and argon proved to be particularly valuable for milling InP/Si layers. To avoid the incongruent evaporation of phosphorous, the latter was performed at liquid nitrogen temperature using 15-20 μA beam current, 5KeV beam voltage and 12° incidence.

Thermal Expansion of GaN at Low Temperatures - a Comparison of Bulk and Homo- and Heteroepitaxial Layers

1999 ◽  
Vol 595 ◽  
Author(s):  
Verena Kirchner ◽  
Heidrun Heinke ◽  
Sven Einfeldt ◽  
Detlef Hommel ◽  
Jaroslaw Z. Domagala ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Low Temperatures ◽  
Lattice Mismatch ◽  
Thermal Strain ◽  
Chemical Vapor ◽  
Thermally Induced ◽  
Thermal Expansion Coefficients ◽  
Bulk Gan ◽  
Expansion Coefficients ◽  
Heteroepitaxial Layers

AbstractThe thermal expansion of different GaN samples is studied by high-resolution Xray diffraction within the temperature range of 10 to 600 K. GaN bulk crystals, a homoepitaxial layer and different heteroepitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) were investigated. Below 100 K the thermal expansion coefficients (TEC) were found to be nearly zero which has to be taken into account when estimating the thermal strain of GaN layers in optical experiments commonly performed at low temperatures. The homoepitaxial layer and the underlying GaN substrate with a lattice mismatch of –6×10−4 showed identical thermal expansion. The comparison between the temperature behavior of lattice parameters of heteroepitaxial layers and bulk GaN points to a superposition of thermally induced biaxial strain and compressive hydrostatic strain.

Optimization of Annealing Conditions for ZnO-based Thin Films Grown Using MOCVD

2014 ◽  
Vol 1675 ◽  
pp. 3-8 ◽  
Author(s):  
Anas Mazady ◽  
Abdiel Rivera ◽  
Mehdi Anwar
Keyword(s):  
Thin Films ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Optical Quality ◽  
Crystal Quality ◽  
Zno Thin Films ◽  
Si Substrates ◽  
Annealing Conditions

ABSTRACTIn this work, effects of thermal annealing on the structural and optical properties of ZnO thin films grown on p-Si and GaN substrates using metalorganic chemical vapor deposition (MOCVD) are investigated. Annealing at 600 °C results in optimum crystal and optical qualities of the ZnO thin films on both substrates. Smaller lattice mismatch between grown ZnO epitaxial layer on GaN substrates results in better film morphology as compared to p-Si substrates. Higher annealing temperature along with a slower thermal ramp provides better crystal quality of ZnO thin films on both substrates. Annealing ZnO thin films at 700 °C with a slower thermal ramp results in better crystal quality as is evident from a 56% reduction in the full-width at half maximum (FWHM) of the (002) peak compared to the as-grown films. The optical quality also enhances with a slower annealing rate. The determination of the optimum annealing conditions for different substrates has important implications in fabricating optimized and efficient ZnO based electronics.

scholarly journals Состояние топологического изолятора в тонких пленках висмута под воздействием плоскостной деформации растяжения

2018 ◽  
Vol 60 (3) ◽  
pp. 452
Author(s):  
Е.В. Демидов ◽  
В.М. Грабов ◽  
В.А. Комаров ◽  
Н.С. Каблукова ◽  
А.Н. Крушельницкий
Keyword(s):  
Carrier Density ◽  
Considerable Increase ◽  
Surface States ◽  
Substrate Material ◽  
Experimental Examination ◽  
Thermal Expansion Coefficients ◽  
Galvanomagnetic Properties ◽  
Bismuth Films ◽  
Expansion Coefficients ◽  
The Difference

AbstractThe results of experimental examination of galvanomagnetic properties of thin bismuth films subjected to plane tensile strain resulting from the difference in thermal expansion coefficients of the substrate material and bismuth are presented. The resistivity, the magnetoresistance, and the Hall coefficient were studied at temperatures ranging from 5 to 300 K in magnetic fields as strong as 0.65 T. Carrier densities were calculated. A considerable increase in carrier density in films thinner than 30 nm was observed. This suggests that surface states are more prominent in thin bismuth films on mica substrates, while the films themselves may exhibit the properties of a topological insulator.

Characterization of Highly Textured PZT Thin Films Grown on LaNiO3 Coated Si Substrates by MOCVD

1997 ◽  
Vol 493 ◽  
Author(s):  
C. H. Lin ◽  
B. M. Yen ◽  
Haydn Chen ◽  
T. B. Wu ◽  
H. C. Kuo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Fatigue Behavior ◽  
Chemical Vapor ◽  
Dielectric Constants ◽  
Preferential Orientation ◽  
Organic Chemical ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Transmission Electron

ABSTRACTHighly textured PbZrxTi1−xO3 (PZT) thin films with x= 0-0.6 were grown on LaNiO3 coated Si substrates at 600 °C by metal-organic chemical vapor deposition (MOCVD). The preferred crystalline orientation of PZT thin films with various Zr concentration were characterized by X-ray diffraction (XRD). Microstructures were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The dielectric constants, hysteresis and fatigue behavior of these thin films were also measured. The relationship between growth rate and the preferential orientation is discussed. Furthermore, the dependence of the electrical properties on Zr concentration and preferential orientation is demonstrated.

Organo-Soluble, Segmented Rigid-Rod Polyimides: Synthesis and Properties

1991 ◽  
Vol 227 ◽  
Author(s):  
F. W. Harris ◽  
S. L. C. Hsu ◽  
C. J. Lee ◽  
B. S. Lee ◽  
F. Arnold ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Oxidative Stability ◽  
Organic Solvents ◽  
Dielectric Constants ◽  
Glass Transition Temperatures ◽  
Thermal Expansion Coefficients ◽  
Rigid Rod ◽  
Expansion Coefficients

ABSTRACTSeveral segmented, rigid-rod polyimides have been prepared that are soluble in organic solvents in their fully imidized form. The polymers were prepared from commercial dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB). Their intrinsic viscosities ranged from 1.0 to 4.9 dL/g. Tough, colorless films could be cast from m-cresol solutions at 100°C. The polymers had glass transition temperatures (Tgs) above 275°C and displayed outstanding thermal and thermo-oxidative stability. Fibers were prepared from the 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA) based polymers that had moduli of 130 GPa and tensile strengths of 3.2 GPa. The thermal expansion coefficients and dielectric constants of thin films (20–25 μm) of the polymers were as low as −2.40×10−6 and 2.5, respectively.

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