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.

A New Quantitative Roughness Measurement and its Application in the Polysilicon/Silicon Dioxide Interface

1992 ◽  
Vol 280 ◽  
Author(s):  
Su-Heng Lin ◽  
Miltiadis K. Hatalis
Keyword(s):  
Silicon Dioxide ◽  
Chemical Vapor ◽  
Interface Roughness ◽  
Height Distribution ◽  
Cross Sectional ◽  
Silicon Thin Films ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
High Temperature Processing

ABSTRACTA quantitative approach for characterizing the interface roughness between two materials by cross sectional transmission electron microscopy (XTEM) is proposed. This approach is based on obtaining an interface height distribution curve (IHDC). The interface roughness can be characterized quantitatively by extracting from IHDC three parameters: the mean, median and maximum interface height. This new method has been applied in the characterization of the interface between thermally grown silicon dioxide and polycrystalline silicon thin films deposited by low pressure chemical vapor deposition. It is shown that high temperature processing yields an interface that has higher roughness.

MORPHOLOGICAL CONTROL OF GaN BUFFER LAYERS GROWN BY MOLECULAR BEAM EPITAXY ON 6H–SiC(0001)

2000 ◽  
Vol 07 (05n06) ◽  
pp. 565-570 ◽  
Author(s):  
CHANGWU HU ◽  
DAVID J. SMITH ◽  
R. B. DOAK ◽  
I. S. T. TSONG
Keyword(s):  
Electron Microscopy ◽  
Substrate Surface ◽  
Supersonic Jet ◽  
Flux Ratio ◽  
Buffer Layers ◽  
Cross Sectional ◽  
Growth Ratio ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

The growth of GaN buffer layers of thickness 10–25 nm directly on 6H–SiC (0001) substrates was studied using low energy electron microscopy, atomic force microscopy and cross-sectional transmission electron microscopy. The Ga flux was supplied by an evaporative source, while the NH3 flux came from a seeded beam supersonic jet source. By monitoring the growth in situ and by suitably adjusting the Ga/NH 3 flux ratio, smooth basal-plane-oriented GaN layers were grown on hydrogen-etched SiC substrates at temperatures in the range of 600–700°C. The growth proceeds via nucleation of small flat islands at the step edges of the 6H–SiC (0001) substrate surface. The islands increase in size with a lateral-to-vertical growth ratio of ~10 and eventually coalesce into a quasicontinuous layer. A highly defective substrate surface was found to be detrimental to the growth of flat buffer layers.

Growth of Ge-on-Si Structures using Remote Plasma-Enhanced Chemical Vapor Deposition

1992 ◽  
Vol 281 ◽  
Author(s):  
Rong Z. Qian ◽  
D. Kinosky ◽  
A. Mahajan ◽  
S. Thomas ◽  
J. Fretwell ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Remote Plasma ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Si Substrates ◽  
Wide Range

ABSTRACTRemote Plasma-enhanced Chemical Vapor Deposition (RPCVD) has been successfully used to grow GexSi1−x/Si (x = 0.1 – 1.0) heteroepitaxial structures at low temperatures (∼450°C). This technique utilizes a noble gas (Ar or He) r-f plasma to decompose reactant gases (SiH4 and GeH4) and drive the chemical deposition reactions in the gas phase as well as on the substrate surface. Growth of pure Ge on Si is of great interest because it provides a promising technique for making suitable low-cost substrates for thin-film Ge photodetectors as well as GaAs devices on Si substrates. The realization of these applications depends on the ability to grow high-quality epitaxial Ge layers on Si substrates. Since GaAs is lattice matched to Ge, growth of Ge layers on Si substrates with good crystalline perfection would permit the integration of GaAs and Si devices. Islanding was observed after the growth of pure Ge films directly on Si(100) for a wide range of plasma powers (7W ∼ 16W) in RPCVD. Cross-sectional TEM analysis showed that the islands have complicated facet structures, including {311} planes. Graded Gex Si1−x buffer layers with different Ge profiles have been used prior to the growth of Ge. It was found that uniform Ge films can be obtained using a buffer with an abrupt Ge profile, and the dislocation density in the Ge film decreases with increasing distance from the substrate.

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.

Silicon Thin Film Growth by Pulsed Plasma CVD under Near-Atmospheric Pressure

2005 ◽  
Vol 891 ◽  
Author(s):  
Hirotatsu Kitabatake ◽  
Maki Suemitsu ◽  
Setsuo Nakajima ◽  
Tsuyoshi Uehara ◽  
Yasutake Toyoshima
Keyword(s):  
Atmospheric Pressure ◽  
Film Growth ◽  
Chemical Vapor ◽  
Pulsed Plasma ◽  
Silicon Thin Film ◽  
Cross Sectional ◽  
Raman Scattering Spectroscopy ◽  
Glass Substrates ◽  
Transmission Electron ◽  
Si Films

ABSTRACTSi Plasma-enhanced chemical vapor deposition (PECVD) at a near-atmospheric pressure (NAP) of 500 Torr has been conducted by using a pulsed-electric-field based NAP-PECVD system. At a growth temperature of 180°C, poly-Si films with a high Raman ratio of 7.4 are obtained on glass substrates, while epitaxial-like growth occurs when Si(100) substrates are employed, as confirmed by Raman-scattering spectroscopy, X-ray diffraction, and a cross-sectional transmission-electron microscopy.

Ion thinning of integrated circuit transverse specimens for transmission electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1426-1427
Author(s):  
F. Shaapur
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Integrated Circuit ◽  
Substrate Surface ◽  
Homogeneous Material ◽  
Material System ◽  
Ion Milling ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Motion Profile

Non-uniform ion-thinning of heterogenous material structures has constituted a fundamental difficulty in preparation of specimens for transmission electron microscopy (TEM). A variety of corrective procedures have been developed and reported for reducing or eliminating the effect. Some of these techniques are applicable to any non-homogeneous material system and others only to unidirectionalfy heterogeneous samples. Recently, a procedure of the latter type has been developed which is mainly based on a new motion profile for the specimen rotation during ion-milling. This motion profile consists of reversing partial revolutions (RPR) within a fixed sector which is centered around a direction perpendicular to the specimen heterogeneity axis. The ion-milling results obtained through this technique, as studied on a number of thin film cross-sectional TEM (XTEM) specimens, have proved to be superior to those produced via other procedures.XTEM specimens from integrated circuit (IC) devices essentially form a complex unidirectional nonhomogeneous structure. The presence of a variety of mostly lateral features at different levels along the substrate surface (consisting of conductors, semiconductors, and insulators) generally cause non-uniform results if ion-thinned conventionally.

{10} edge dislocations in YSZ films grown on (100)MgO by PLD

1994 ◽  
Vol 52 ◽  
pp. 530-531
Author(s):  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Semiconductor Lasers ◽  
Vapor Deposition ◽  
Substrate Surface ◽  
Laser System ◽  
Average Energy ◽  
Target Material ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Organic Chemical

Yttria-stabilized zirconia (YSZ) is currently used in a variety of applications including oxygen sensors, fuel cells, coatings for semiconductor lasers, and buffer layers for high-temperature superconducting films. Thin films of YSZ have been grown by metal-organic chemical vapor deposition, electrochemical vapor deposition, pulse-laser deposition (PLD), electron-beam evaporation, and sputtering. In this investigation, PLD was used to grow thin films of YSZ on (100) MgO substrates. This system proves to be an interesting example of relationships between interfaces and extrinsic dislocations in thin films of YSZ.In this experiment, a freshly cleaved (100) MgO substrate surface was prepared for deposition by cleaving a lmm-thick slice from a single-crystal MgO cube. The YSZ target material which contained 10mol% yttria was prepared from powders and sintered to 85% of theoretical density. The laser system used for the depositions was a Lambda Physik 210i excimer laser operating with KrF (λ=248nm, 1Hz repetition rate, average energy per pulse of 100mJ).

Post Oxidation Anneal and Re-Oxidation Effects in 5 nm SiO2 Films

1986 ◽  
Vol 76 ◽  
Author(s):  
L. Dori ◽  
M. Arienzo ◽  
Y. C. Sun ◽  
T. N. Nguyen ◽  
J. Wetzel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Dioxide ◽  
Oxygen Vacancies ◽  
Interface Roughness ◽  
Cross Sectional ◽  
Oxide Charge ◽  
Transmission Electron ◽  
Redistribution Of Hydrogen ◽  
Transmission Electron Microscopy Cross

ABSTRACTUltrathin silicon dioxide films, 5 nm thick, were grown in a double-walled furnace at 850°C in dry O2. A consistent improvement in the electrical properties is observed following the oxidation either with a Post-Oxidation Anneal (POA) at 1000°C in N2 or with the same POA followed by a short re-oxidation (Re-Ox) step in which 1 nm of additional oxide was grown. We attribute these results to the redistribution of hydrogen and water related groups as well as to a change in the concentration of sub-oxide charge states at the Si-SiO2 interface. A further improvement observed after the short re-oxidation step had been attributed to the filling of the oxygen vacancies produced during the POA. High resolution Transmission Electron Microscopy cross-sectional observations of the Si-iSO2 interface have evidenced an increase in the interface roughness after the thermal treatment at high temperature. These results are in agreement with recent XPS data.

Growth of Si1−xGex, Strained Layers Using Atmospheric-Pressure CVD

1991 ◽  
Vol 220 ◽  
Author(s):  
F. Namavar ◽  
J. M. Manke ◽  
E. P. Kvam ◽  
M. M. Sanfacon ◽  
C. H. Perry ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Defect Density ◽  
Chemical Vapor ◽  
Good Growth ◽  
X Ray Diffraction ◽  
Strained Layers ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Film Defect

ABSTRACTThe objective of this paper is to demonstrate the epitaxial growth of SiGe strained layers using atmospheric-pressure chemical vapor deposition (APCVD). We have grown SiGe layers with various thicknesses and Ge concentrations at temperatures ranging from 800–1000°C. The samples were studied using a variety of methods, including transmission electron microscopy (TEM), high resolution X-ray diffraction (HRXRD) and Raman spectroscopy (RS). Both HRXRD and RS results indicate that samples with about 10% Ge and a thickness of about 1000 Å are almost fully strained. TEM analyses of these samples indicate a film defect density less than 105/cm2. SIMS results indicate that the oxygen concentration in the epitaxial layers is lower than that found in CZ substrates.Our analyses also indicate that as-grown epitaxial Ge layers several microns thick have a defect density less than 107/cm2. The relatively low defect density in both SiGe and Ge layers grown on Si has been attributed to far higher dislocation glide velocity at the relatively elevated growth temperatures employed in CVD and to very good growth cleanliness.

Substrate Dependence of Microcrystalline Silicon Growth with SiH4 Diluted by Ar

2014 ◽  
Vol 936 ◽  
pp. 264-268
Author(s):  
Hua Cheng ◽  
Yong Chan Qian ◽  
Jun Xue
Keyword(s):  
Deposition Rate ◽  
Electron Cyclotron Resonance ◽  
Substrate Surface ◽  
Gaseous Mixture ◽  
Film Surface ◽  
Chemical Vapor ◽  
Preferred Orientation ◽  
Initial Stage ◽  
Substrate Dependence ◽  
Si Films

Microcrystalline Si films were deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) using Ar diluted SiH4gaseous mixture. The effects of the substrate on deposition rate, preferred orientation and roughness of the films were investigated. The results show that, the influence of the substrate surface chemical nature on the deposition rate is significant in the initial stage of the growth. And considering the crystallinity and roughness of the films, the substrate is favored in its preferred orientation with a rougher surface. Based on these results, it is confirmed that the combination of diffusion and etching is indispensable to describe the deposition of μc-Si with SiH4diluted by Ar, and the mechanism of μc-Si growth could be controlled by diffusion of Si and etching of the Ar+on the film surface.

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