Raman Spectroscopy of Epitaxial Si/Si1-xGe, xHeterostructures

1998 ◽  
Vol 533 ◽  
Author(s):  
Ran Liu ◽  
Stefan Zollner ◽  
Ming Liaw ◽  
David O'meara ◽  
Nigel Cave
Keyword(s):  
Raman Spectroscopy ◽  
Thermal Treatment ◽  
Raman Scattering ◽  
Buffer Layer ◽  
Excellent Agreement ◽  
Lattice Mismatch ◽  
Theoretical Curve ◽  
Sum Rule ◽  
Si Substrates ◽  
Strain Coefficient

AbstractRaman scattering studies were carried out on epi Si/Si1-xGex (x = 0.1 to 0.3) heterostructures consisting of a thin Si cap layer (100 - 400 A˚), a grade-down Si1-xGex layer, a constant Si1-xGex, buffer layer and a grade-up graded Si1-xGex layer on (100) oriented Si substrates. Different Ge composition, Si1-xGex layer thicknesses and thermal treatment were used to achieve different relaxation in the Si1-xGex layers. It has been revealed that, to a very good approximation, the absolute strains in the cap Si and constant Si1-xGex layers follow a simple sum-rule that is imposed by the lattice mismatch between unstrained Si and completely relaxed Si1-x Gex. This sum rule can be used to determine the Ge composition and stresses in both cap Si and constant Si1-xGex layers. Excellent agreement was found between the theoretical curve obtained with LO phonon strain coefficient b=−930cm−1 and the experimental total strain for all samples, regardless of the degree of the relaxation of the grade-up Si1-xGex layer.

Growth and properties of epitaxial PbSe on Si(111) and Si(100) without buffer layer

1995 ◽  
Vol 379 ◽  
Author(s):  
P. Müller ◽  
A.N. Tiwari ◽  
H. Zogg
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Infrared Detector ◽  
Device Fabrication ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
High Quality ◽  
Si Substrates ◽  
Large Lattice ◽  
Large Lattice Mismatch

Narrow gap IV-VI materials like PbS, PbSnSe and PbSnTe are used for infrared detector device fabrication [1,2]. Earlier an intermediate Ila-fluoride buffer layer, which consisted of a BaF2/CaF2-stack of about 2000 Å thickness, was used to get epitaxial high quality layers on silicon substrates. This buffer is now reduced to a much thinner layer of only about 20 Å thick CaF2, regardless the large lattice mismatch between layer and substrate [3,4,5]. The question therefore arises if high quality IV-VI layers can be grown on Si-substrates without any buffer layer as e.g. in CdTe/Si or GaAs/Si systems.The aim of this work is to grow IV-VI layers directly on Si-substrates without any buffer layers to study the growth kinetics and epitaxial quality. PbSe was chosen as a representant of IV-VI materials, and layers were grown on (111)- and (100)-oriented silicon substrates.

Growth of GaAs on Si and its Application to FETs and LEDs

1986 ◽  
Vol 67 ◽  
Author(s):  
Masahiro Akiyama ◽  
Yoshihiro Kawarada ◽  
Seiji Nishi ◽  
Takashi Ueda ◽  
Katsuzo Kaminishi
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Antiphase Domain ◽  
Thin Layers ◽  
The Other ◽  
Heteroepitaxial Growth ◽  
Si Substrates ◽  
Large Lattice ◽  
Strained Layer Superlattice ◽  
Large Lattice Mismatch

In recent years, the heteroepitaxial growth of GaAs layers on Si substrates has been gained an increasing interest [1 - 14]. GaAs is one of the most important III-V materials and has been well studied and used for optical and electrical devices. On the other hand, with Si we have large size wafers of superior quality and sophisticated technologies and Si is a main material for semiconductor industries. Therefore, GaAs/Si system has possibilities for realizing new types of functional devices or ICs with GaAs and Si devices. This system, however, has two serious problems. One is the large lattice mismatch of about 4 % between these materials and the other is the polar on nonpolar problem i.e., the formation of an antiphase domain disorder. It was reported that when (211)-oriented Si substrates were used, there was no problem of the formation of an antiphase domain structure 5. For growing materials on lattice mismatched substrates, it was reported that the thin layers deposited at low temperatures were effective to relax the lattice mismatches for the systems such as SiC on Si[15] and Si on saphire [16]. In GaAs/Si system, the Ge buffer layer has been used to relax the lattice mismatch[17 - 22] It was also reported that the composite strained layer superlattice with GaP/GaAsP and GaAsP/GaAs was very effective as a buffer layer[23 - 25].

Microstructures of GaN films deposited on (001) and (111) Si substrates using electron cyclotron resonance assisted-molecular beam epitaxy

1994 ◽  
Vol 9 (9) ◽  
pp. 2370-2378 ◽  
Author(s):  
S.N. Basu ◽  
T. Lei ◽  
T.D. Moustakas
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Cyclotron Resonance ◽  
Molecular Beam ◽  
Electron Cyclotron Resonance ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Electron Cyclotron ◽  
Si Substrates ◽  
Zinc Blende

The microstructures of GaN films, grown on (001) and (111) Si substrates by a two-step method using Electron Cyclotron Resonance assisted-Molecular Beam Epitaxy (ECR-MBE), were studied by electron microscopy techniques. Films grown on (001) Si had a predominantly zinc-blende structure. The GaN buffer layer, grown in the first deposition step, accommodated the 17% lattice mismatch between the film and substrate by a combination of misoriented domains and misfit dislocations. Beyond the buffer layer, the film consisted of highly oriented domains separated by inversion domain boundaries, with a substantial decrease in the defect density away from the interface. The majority of defects in the film were stacking faults, microtwins, and localized regions having the wurtzite structure. The structure of the GaN films grown on (111) Si was found to be primarily wurtzite, with a substantial fraction of twinned zinc-blende phase. Occasional wurtzite grains, misoriented by a 30°twist along the [0001] axis, were also observed. A substantial diffusion of Si was seen in films grown on both substrates.

Growth and Properties of GaN/Si Heterojunction

2005 ◽  
Vol 480-481 ◽  
pp. 531-536
Author(s):  
Hassan Zainuriah ◽  
Sha Shiong Ng ◽  
G.L. Chew ◽  
F.K. Yam ◽  
Mat Johar Abdullah ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Buffer Layer ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Wide Band ◽  
Hexagonal Wurtzite Structure ◽  
Schottky Barriers ◽  
Full Characterization ◽  
Si Substrates ◽  
Aln Buffer

Gallium nitride (GaN) is a highly promising wide band gap semiconductor with applications in high power electronic and optoelectronic devices. Thin films of GaN are most commonly grown in the hexagonal wurtzite structure on sapphire substrates. Growth of GaN onto silicon substrates offers a very attractive opportunity to incorporate GaN devices onto silicon based integrated circuits. Although direct epitaxial growth of GaN films on Si substrates is a difficult task (mainly due to the 17% lattice mismatch present), substantial progress in the crystal quality can be achieved using a buffer layer. A full characterization of the quality of the material needs to be assessed by a combination of different techniques. In this work, a detailed characterization study of GaN thin film grown on Si(111) with AlN buffer layer by low pressure metalorganic chemical vapor deposition (LP-MOCVD) was carried out. Post deposition analysis includes scanning electron microscopy (SEM), x-ray diffraction (XRD), Hall and infrared (IR) spectroscopy techniques. The IR spectra were compared to the calculated spectra generated with a damped single harmonic oscillator model. Through this method, a complete set of reststrahlen parameters (such as ε∞, S, wTO, γ) of the GaN epilayer were obtained. Our results show that the GaN film has a single crystalline structure. Current-voltage characteristics (I-V) of this GaN/Si heterojunction were measured at room temperature. Rectification behavior was observed for this anisotype heterojunction. The electrical characteristics of Ni Schottky barriers on this unintentionally doped n-type film were also investigated. The barrier height of Ni/GaN Schottky barriers has been determined to be 0.93 eV by I-V measurement.

Growth Studies of Heteroepitaxial Ge Films ON Si

1988 ◽  
Vol 116 ◽  
Author(s):  
D.J. Heim ◽  
T.G. Holesinger ◽  
K.M. Lakin ◽  
H.R. Shanks
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Lattice Mismatch ◽  
Cluster Beam ◽  
Single Crystalline ◽  
Si Substrates ◽  
Gaas On Si ◽  
Growth Studies ◽  
Rapid Monitoring ◽  
Computer Controlled

AbstractOne of the approaches to the growth of GaAs on Si substrates involves the use of a heteroepitaxial buffer layer such as Ge to reduce lattice mismatch. Recently, we have had success in growing heteroepitaxial Ge films on low temperature (∼275-500°C) Si substrates by the ionized cluster beam (ICB) technique. The design of a computer-controlled phase modulated ellipsometer for rapid monitoring of the initial stages of nucleation will be described. Ellipsometric data for single crystalline, polycrystalline and amorphous morphologies are reported.

Photoluminescence and Raman Spectroscopy of Cubic SiC Grown by Chemical Vapor Deposition on Si Substrates

1985 ◽  
Vol 46 ◽  
Author(s):  
J.A. Freitas ◽  
S.G. Bishop ◽  
A. Addamiano ◽  
P.H. Klein ◽  
H.J. Kin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Si Substrates ◽  
Defect Complexes ◽  
Substrate Removal ◽  
Nitrogen Donor ◽  
Donor Acceptor

AbstractThin films of cubic SiC were grown on Si substrates by a new CVD heteroepitaxial technique. The cubic polytype and crystal quality were verified by room temperature Raman spectroscopy. Low temperature photoluminescence (PL) studies detected nitrogen donor bound excitons, N-Al donor-acceptor pairs in Al-doped samples, and some defect complexes usually observed only in irradiated samples. Evidence of strain due to the Si-SiC lattice mismatch was observed in both the Raman and PL spectra and the effects of substrate removal and high temperature annealing on these optical spectra were studied.

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ZNO FILMS ON SILICON SUBSTRATE WITH ITO BUFFER LAYER

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1764-1770 ◽  
Author(s):  
C.-W. ZOU ◽  
W. GAO
Keyword(s):  
Mechanical Properties ◽  
Buffer Layer ◽  
Mechanical Performance ◽  
Lattice Mismatch ◽  
Buffer Layers ◽  
Zno Films ◽  
Si Substrates ◽  
Microstructure And Mechanical Properties ◽  
Deformation Behaviors ◽  
Continuous Stiffness Measurement

ZnO thin films were prepared by an unbalanced magnetron sputter on silicon substrates and glass slides. An ITO layer was applied on Si substrate as a buffer layer. Microstructure and mechanical deformation behaviors of the ZnO films were investigated by XRD, SEM and nanoindentation methods. Results showed that ITO buffer layer plays an important role for ZnO heteroepitaxy growth on Si substrates. The strains at the interface induced by the lattice mismatch of Si and ZnO are repressed. As a result, ZnO films with the buffer layers showed larger grain size and better crystallinity. The hardness and modulus of ZnO films with buffer layer decreased. Continuous stiffness measurement (CSM) technique was also used to investigate the effects of buffer layer and substrate materials on the mechanical performance of the prepared ZnO films. The relationship between microstructure and mechanical properties of ZnO films are discussed based on the experimental results.

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.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

In-Situ Study of NiO Growth on Textured Nickel Tape Using Environmental Scanning Electron Microscope (ESEM) and Hot Stage

2001 ◽  
Vol 7 (S2) ◽  
pp. 1276-1277
Author(s):  
Y. Akin ◽  
R.E. Goddard ◽  
W. Sigmund ◽  
Y.S. Hascicek
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Dip Coating ◽  
Buffer Layers ◽  
Superconducting Film ◽  
Environmental Scanning ◽  
Cold Rolling And Annealing

Deposition of highly textured ReBa2Cu3O7−δ (RBCO) films on metallic substrates requires a buffer layer to prevent chemical reactions, reduce lattice mismatch between metallic substrate and superconducting film layer, and to prevent diffusion of metal atoms into the superconductor film. Nickel tapes are bi-axially textured by cold rolling and annealing at appropriate temperature (RABiTS) for epitaxial growth of YBa2Cu3O7−δ (YBCO) films. As buffer layers, several oxide thin films and then YBCO were coated on bi-axially textured nickel tapes by dip coating sol-gel process. Biaxially oriented NiO on the cube-textured nickel tape by a process named Surface-Oxidation- Epitaxy (SEO) has been introduced as an alternative buffer layer. in this work we have studied in situ growth of nickel oxide by ESEM and hot stage.Representative cold rolled nickel tape (99.999%) was annealed in an electric furnace under 4% hydrogen-96% argon gas mixture at 1050°C to get bi-axially textured nickel tape.

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