Reduction of Strain in Epitaxial GaAs on CaF2/Si Substrates

1988 ◽  
Vol 116 ◽  
Author(s):  
Shin Hashimoto ◽  
L.J. Schowalter ◽  
G.A. Smith ◽  
E.Y. Lee ◽  
W.M. Gibson ◽  
...  
Keyword(s):  
Buffer Layers ◽  
Epitaxial Gaas ◽  
Si Substrates ◽  
Ion Channeling

AbstractThis paper reports on strains in epitaxial GaAs layers grown on CaF2/Si(001) and CaF2/Si(111) heteroepitaxial substrates investigated by MeV 4He+; ion channeling. The results indicate that the CaF2 buffer layers reduce strain in the GaAs.

Microstructure of thin layers of MBE-grown GaAs on Si substrates

1986 ◽  
Vol 67 ◽  
Author(s):  
S. J. Rosner ◽  
S. M. Koch ◽  
J. S. Harris ◽  
S. Laderman
Keyword(s):  
Structural Evolution ◽  
Normal Growth ◽  
Optical Quality ◽  
Thin Layers ◽  
Buffer Layers ◽  
Initial Growth ◽  
Slow Growth Rate ◽  
Si Substrates ◽  
Ion Channeling

ABSTRACTThe ability to grow high quality epitaxial GaAs films directly on Si substrates has recently been demonstrated by Molecular Beam Epitaxy. Many of the most successful growth techniques include initial growth at low temperatures and slow growth rate to nucleate the compound on the elemental semiconductor with subsequent normal growth under conditions used for homoepitaxial GaAs MBE. The mechanisms for the success of this method are still poorly understood. This work focusses on a study of the structural evolution of this low temperature initial layer and conventionally grown overlayer. Thin films in the 5 to 300 nm range were used to evaluate the effect of the temperature and thickness on the growth process. Thicker films, described elsewhere, were used to evaluate the crystalline and optical quality of potential device layers.The structure of the thin buffer layers was studied as a function of both temperature and thickness. The crystalline quality of these layers was found to be quite poor, with substantial disorder at the GaAs/Si interface. The quality improved slowly as a function of thickness. The effect of the conventional overgrowth on this initil layer was also investigated. It was found that the quality of the low tumperature layer improved as normal overgrowth continued, as measured by ion channeling aligned yields. After 200 nm of overgrowth, ion channeling aligned yields from the material at the interface had declined substantially. This indicates that substantial regrowth and annealing of defects occurs as growth continues. These observations are further confirmed by TEM.

Strain in Epitaxial GaAs on Si and CaF2/Si

1987 ◽  
Vol 102 ◽  
Author(s):  
L. J. Schowalter ◽  
Shin Hashimoto ◽  
G. A. Smith ◽  
W. M. Gibson ◽  
N. Lewis ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Gaas Layer ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Si Substrate ◽  
High Quality ◽  
Strain Measurements ◽  
Epitaxial Gaas ◽  
Ion Channeling ◽  
Gaas On Si

ABSTRACTIn this paper, ion channeling techniques are used to show that epitaxial GaAs layers grown on vicinal Si(001) wafers do not have their [001] axis precisely aligned with that of the Si substrate. Instead, the [001] axis of the GaAs layer is found to be tilted toward the surface normal of the Si substrate. This tilt was found to be ∼0.2° on vicinal Si(001) substrates which have their [001] axis tilted 4° toward the [110] azimuth. It is speculated that this misalignment is reponsible for the residual density of threading dislocations in the GaAs on Si layer. An approach described here, which can be used to avoid strain in the GaAs layer, is to grow a CaF2 buffer layer between the Si substrate and the epitaxial GaAs layer. High quality epitaxial GaAs layers have been obtained on both CaF 2 /Si(001) and CaF 2 /Si(111) substrates. Strain measurements of the epitaxial GaAs on the CaF 2 buffer layers indicate that these layers have strains below our detection limits.

Effects of the Sputtering Time of AlN Buffer Layer on the Quality of ZnO Thin Films

2014 ◽  
Vol 881-883 ◽  
pp. 1117-1121 ◽  
Author(s):  
Xiang Min Zhao
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Rf Magnetron Sputtering ◽  
Buffer Layers ◽  
Zno Thin Films ◽  
Zno Films ◽  
Si Substrates ◽  
Atomic Force ◽  
Structure Morphology ◽  
Aln Buffer

ZnO thin films with different thickness (the sputtering time of AlN buffer layers was 0 min, 30 min,60 min, and 90 min, respectively) were prepared on Si substrates using radio frequency (RF) magnetron sputtering system.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO thin films with different sputtering time of AlN buffer layer,and for the better growth of ZnO films, the optimal sputtering time is 60 min.

Defect Reduction in GaAs Epilayers on Si Substrates Using Strained Layer Superlattices

1987 ◽  
Vol 91 ◽  
Author(s):  
N. El-Masry ◽  
N. Hamaguchi ◽  
J.C.L. Tarn ◽  
N. Karam ◽  
T.P. Humphreys ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Defect Reduction ◽  
Strained Layer ◽  
Si Substrates ◽  
Density Of Dislocations ◽  
Strained Layer Superlattice ◽  
Strained Layer Superlattices

ABSTRACTInxGa11-xAs-GaAsl-yPy strained layer superlattice buffer layers have been used to reduce threading dislocations in GaAs grown on Si substrates. However, for an initially high density of dislocations, the strained layer superlattice is not an effective filtering system. Consequently, the emergence of dislocations from the SLS propagate upwards into the GaAs epilayer. However, by employing thermal annealing or rapid thermal annealing, the number of dislocation impinging on the SLS can be significantly reduced. Indeed, this treatment greatly enhances the efficiency and usefulness of the SLS in reducing the number of threading dislocations.

Monolithic integration of room-temperature cw GaAs/AlGaAs lasers on Si substrates via relaxed graded GeSi buffer layers

2003 ◽  
Vol 93 (1) ◽  
pp. 362-367 ◽  
Author(s):  
Michael E. Groenert ◽  
Christopher W. Leitz ◽  
Arthur J. Pitera ◽  
Vicky Yang ◽  
Harry Lee ◽  
...  
Keyword(s):  
Room Temperature ◽  
Monolithic Integration ◽  
Buffer Layers ◽  
Si Substrates

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.

Influence of Interface States on Output Characteristics of 4H-SiC MESFETs on Semi–Insulating Substrates

2000 ◽  
Vol 640 ◽  
Author(s):  
Nabil Sghaier ◽  
Abdel K. Souifi ◽  
Jean-Marie Bluet ◽  
Manuel Berenguer ◽  
Gérard Guillot ◽  
...  
Keyword(s):  
Gate Voltage ◽  
Frequency Dispersion ◽  
Buffer Layers ◽  
Si Substrate ◽  
Substrate Interface ◽  
Si Substrates ◽  
Kink Effect ◽  
Parasitic Effect ◽  
Output Characteristics ◽  
Output Conductance

ABSTRACTThe aim of this work is to study the origin of parasitic phenomena in the output characteristics of 4H-SiC MESFETs on semi-insulating (SI) substrates with various buffer layers. Ids-Vds measurements as a function of temperature have first been performed. Different parasitic effects such as kink effect, hysteresis effect when the gate voltage is successively increased or decreased, or changes in the output characteristics after a high drain polarization are presented. Random Telegraph Signal (RTS) measurements and frequency dispersion of the output conductance have next been realized. From the obtained results, we propose that the parasitic effect on the output characteristics are correlated with the presence of deep levels located near the semi -insulating substrate interface. The main observed trap is tentatively attributed to the presence of Vanadium in the SI substrate.

Ultra-thin strain relaxed SiGe buffer layers with 40% Ge

2004 ◽  
Vol 809 ◽  
Author(s):  
Klara Lyutovich ◽  
Erich Kasper ◽  
Michael Oehme
Keyword(s):  
Surface Morphology ◽  
Point Defect ◽  
Strain Relaxation ◽  
Layer Growth ◽  
Buffer Layers ◽  
In Situ Monitoring ◽  
Process Window ◽  
Growth Stages ◽  
Growth Monitoring ◽  
Si Substrates

ABSTRACTVirtual substrates with ultra-thin SiGe strain relaxed buffers have been grown on Si substrates by a method employing point defect supersaturation in the growing layers. A concept of the point defect influence on the strain relaxation and on defect interactions in layers has been proposed. A method is developed to increase the degree of relaxation in sub-100 nm SiGe buffer layers and to provide a smooth surface morphology. Layer growth has been realized by solid source molecular beam epitaxy in a chamber equipped with an in situ monitoring system. One of the growth stages, performed at a very low temperature, serves the generation of point defects. Strain relaxation tunable up to the high degree and a crosshatch-free surface morphology are demonstrated in 40nm thick SiGe buffers which contain 40-45% Ge.Growth monitoring enables the control of the process window and the layer crystallization by a chosen mechanism.Virtual substrates produced by the described method were successfully tested in nMODFET structures.

scholarly journals InN/InGaN quantum dot electrochemical devices: new solutions for energy and health

2017 ◽  
Vol 4 (2) ◽  
pp. 184-195 ◽  
Author(s):  
Richard Nötzel
Keyword(s):  
Hydrogen Generation ◽  
Buffer Layers ◽  
Nitride Semiconductors ◽  
Solar Hydrogen ◽  
Si Substrates ◽  
Novel Device ◽  
Direct Growth ◽  
Electrochemical Devices ◽  
Application Fields ◽  
Opening Up

AbstractA review is given of the exceptional electrochemical performance of epitaxial InN/InGaN quantum dots (QDs) as photoelectrodes for solar hydrogen generation by water splitting, as biosensor transducers and as anion-selective electrodes, and they are also evaluated as supercapacitor electrodes. The performance is benchmarked against the best performances of other reported materials and nanostructures. A model based on the unique interplay of surface and quantum properties is put forward to understand the boost of catalytic activity and anion selectivity interlinking quantum nanostructure physics with electrochemistry and catalysis. Of equal impact is the direct growth on cheap Si substrates without any buffer layers, allowing novel device designs and integration with Si technology. This makes the InN/InGaN QDs viable, opening up new application fields for III-nitride semiconductors.

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