Cross-Section Transmission Electron Microscope Study of Ni/Au/Ge/Au Ohmic Contact to Gallium Arsenide

1986 ◽  
Vol 77 ◽  
Author(s):  
Taeil Kim ◽  
D. D. L. Chung ◽  
S. Mahajan
Keyword(s):  
Cross Section ◽  
Solid Phase ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Interface Area ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Transmission Electron Microscope Study ◽  
Metallurgical Reactions

ABSTRACTThe interfacial structures resulting from the metallurgical reactions between a Ni/Au/Ge/Au film and (100) GaAs substrate were studied by cross-section TEM. Annealing at 300 – 350°C causes a complicated solid-solid phase reaction, resulting in the multilayer structure of Ni2Ge/Au7Ga2/NiAs/Au7Ga,/GaAs. The contact shows non-ohmic character, since most of the doping element Ge is trapped in the surface Ni2Ge layer When the contact is annealed at above 400°C. the layered structure is destroyed because one of the phases (Au-Ga) becomes liquid but other phases (Ni-Ge, Ni-As) remain solid Ge, which is captured in the surface layer, diffuses out of the Ni2Ge phase into the contact/GaAs interface through the Au-rich melt. Above this temperature, a Ge-doped n+ region is probably formed at the NiAs/GaAs interface and the contact becomes ohmic. With increasing annealing temperature, continuous grain growth of NiAs is found to occur and the NiAs/GaAs interface area increases. Thus the ohmic behavior of Au-Ge-Ni on n-GaAs can be explained by the low barrier height of the NiAs/GaAs interface and the formation of Ge-doped n+ region under the NiAs phase.

The Synthesis and Properties Studying of 1-D TaS2 Nanostructure

2007 ◽  
Vol 353-358 ◽  
pp. 2139-2142
Author(s):  
Chang Sheng Li ◽  
Yan Qing Liu ◽  
Jun Mao Li
Keyword(s):  
Large Scale ◽  
Solid Phase ◽  
Average Diameter ◽  
Test System ◽  
Lubricating Oil ◽  
One Dimension ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Transmission Electron ◽  
Specimen Test

large-scale and elegant one-dimension tubular nanostructure TaS2, have been generated successfully employing solid-phase reaction growth with tantalum and sulfur powders. Detailed experimental procedures, and the characterization of associated product, have been evaluated using transmission electron microscopy (TEM) and other techniques. The results show that the reaction yielded a lot of one dimension nanostructures of TaS2 with average diameter of one hundred nanometers and length of several micrometers (or several ten micrometers). Moreover, effect of TaS2 nanostructure, as additive in commercial lubricating oil T40, was initially measured by UMT Multi-specimen Test System (UMT-2). The results show, as additive, antiwear and bearing weight ability of 1-D TaS2 nanostructure, excelled ordinary lubricating oil at atmosphere.

scholarly journals Formation Mechanism of High-Purity Ti2AlN Powders under Microwave Sintering

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5356
Author(s):  
Weihua Chen ◽  
Jiancheng Tang ◽  
Xinghao Lin ◽  
Yunlong Ai ◽  
Nan Ye
Keyword(s):  
Electron Microscopy ◽  
Formation Mechanism ◽  
High Purity ◽  
Solid Phase ◽  
Raw Materials ◽  
Microwave Sintering ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Scanning Calorimetry ◽  
Transmission Electron

In the present study, high-purity ternary-phase nitride (Ti2AlN) powders were synthesized through microwave sintering using TiH2, Al, and TiN powders as raw materials. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were adopted to characterize the as-prepared powders. It was found that the Ti2AlN powder prepared by the microwave sintering of the 1TiH2/1.15Al/1TiN mixture at 1250 °C for 30 min manifested great purity (96.68%) with uniform grain size distribution. The formation mechanism of Ti2AlN occurred in four stages. The solid-phase reaction of Ti/Al and Ti/TiN took place below the melting point of aluminum and formed Ti2Al and TiN0.5 phases, which were the main intermediates in Ti2AlN formation. Therefore, the present work puts forward a favorable method for the preparation of high-purity Ti2AlN powders.

Stable Solid-Phase Ohmic Contacts to n-GaAs with Diffusion Barriers

1988 ◽  
Vol 126 ◽  
Author(s):  
E. Kolawa ◽  
C. W. Nieh ◽  
W. Flick ◽  
J. Molarius ◽  
M-A. Nicolet
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ohmic Contacts ◽  
Solid Phase ◽  
Diffusion Barriers ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Resistivity Measurements ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTContacts to GaAs substrates with n-type epilayers formed by GaAs/Ni/Ge/WN/Au, GaAs/Ni/Ge/Ni/WN/Au and GaAs/Ge/ Ni/WN/Au systems were investigated. Ohmic contacts in these systems were formed by a solid-phase reaction between Ni/Ge and GaAs. Interfacial reaction and electrical properties of these contacts are characterized by backscattering spectrometry, transmission electron microscopy and contact resistivity measurements. Resistivities in the 10−δ Ω cm range are achieved.

Thickness Dependent Phase Formation in Fe Thin Film and Si Substrate Solid Phase Reaction

1995 ◽  
Vol 402 ◽  
Author(s):  
G Y. Molnár ◽  
G. Pető ◽  
E. Zsoldos ◽  
Z. E. Horváth ◽  
N. Q. Khánh
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Phase Formation ◽  
Solid Phase ◽  
Iron Film ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Si Substrate ◽  
Transmission Electron ◽  
Initial Iron

AbstractThe solid phase reaction of Fe thin films with (111) Si substrate was investigated at constant annealing temperature and time (700°C, 7 minutes) as a function of the initial iron film thickness (from 5 nm to 27.5 um in 2.5 nm steps). The formed phases were analysed by X-ray diffraction, Rutherford backscattering and transmission electron microscopy and optical microscopy.After annealing FeSi phase was detected in the thinner samples. Samples with Fe layers thicker than 12.5 nm contained a β-FeSi2 phase. This special phase sequence was explained with the help of a nucleation controlled phase formation model, taking into consideration the critical radius of nuclei of the new phase. The advantages of using the film thickness as a variable during investigation of solid phase thin film reactions and the probable substrate effects are also discussed.

Epitaxial Formation of Rare Earth Silicides by Rapid Annealing

1985 ◽  
Vol 54 ◽  
Author(s):  
J. A. Knapp ◽  
S. T. Picraux
Keyword(s):  
Rare Earth ◽  
Solid Phase ◽  
Ion Beam ◽  
Epitaxial Films ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Si Substrates ◽  
Transmission Electron ◽  
Random Array ◽  
Liquid Phase Reaction

ABSTRACTRapid electron beam and lamp heating have been used to form thin epitaxial films of rare-earth suicides by reacting overlayers of the rare earths with (111) Si substrates. Of the metals Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, all but Gd are found to form epitaxial suicide layers by rapid solid-phase reaction, while suicides of Gd, Dy, Tm, Yb and Lu have been formed epitaxially by liquid phase reaction. For all but Er this is the first demonstration of epitaxial growth on Si. Details obtained from ion beam channeling analysis and transmission electron microscopy confirm the expected epitaxial structure and also show that the Si vacancies in the suicide form an ordered superlattice, rather than a random array as had been assumed before.

Solid-Phase Epitaxial Regrowth of GaAs by in-situ Controlled Intermediate Phase Decomposition

1998 ◽  
Vol 4 (S2) ◽  
pp. 634-635
Author(s):  
J.K. Farrer ◽  
D.A. Caldwell ◽  
C.J. Palmstrom ◽  
C.B. Carter
Keyword(s):  
Intermediate Phase ◽  
Solid Phase ◽  
Metal Layer ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Tem Analysis ◽  
Epitaxial Regrowth ◽  
Transmission Electron ◽  
Subsequent Decomposition

A transmission electron microscopy (TEM) analysis on the regrowth of GaAs by a two-stage reaction between a metal layer (M) and a GaAs substrate is presented. The first stage of the regrowth process is the consumption of GaAs in a low temperature reaction with the metal layer, producing an intermediate phase of (MxGaAs). A second solid-phase reaction, induced by the deposition of Ga or As, results in the decomposition of the intermediate phase and the epitaxial regrowth of a layer of GaAs. The sample growth and reactions were performed in-situ in a molecular beam epitaxy system, using Ni for the metal and As deposition for the second reaction. TEM data confirm the formation of the ternary phase, NixGaAs, and its subsequent decomposition into NiAs and GaAs by reacting with the deposited As. A layer of AlGaAs, 100 nm thick, was grown in all samples as a marker.

scholarly journals Multifunctional GaFeO3 Obtained via Mechanochemical Activation Followed by Calcination of Equimolar Nano-System Ga2O3–Fe2O3

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 57
Author(s):  
Lucian Diamandescu ◽  
Felicia Tolea ◽  
Marcel Feder ◽  
Florin Vasiliu ◽  
Ionel Mercioniu ◽  
...  
Keyword(s):  
Mechanochemical Activation ◽  
Solid Phase ◽  
High Energy ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Transmission Electron ◽  
Subsequent Calcination ◽  
20 Nm

The equimolar oxide mixture β-Ga2O3—α-Fe2O3 was subjected to high-energy ball milling (HEBM) with the aim to obtain the nanoscaled GaFeO3 ortho-ferrite. X-ray diffraction, 57Fe Mössbauer spectroscopy, and transmission electron microscopy were used to evidence the phase structure and evolution of the equimolar nano-system β-Ga2O3—α-Fe2O3 under mechanochemical activation, either as-prepared or followed by subsequent calcination. The mechanical activation was performed for 2 h to 12 h in normal atmosphere. After 12 h of HEBM, only nanoscaled (~20 nm) gallium-doped α-Fe2O3 was obtained. The GaFeO3 structure was obtained as single phase, merely after calcination at 950 °C for a couple of hours, of the sample being subjected to HEBM for 12 h. This temperature is 450 °C lower than used in the conventional solid phase reaction to obtain gallium orthoferrite. The optical and magnetic properties of representative nanoscaled samples, revealing their multifunctional character, were presented.

scholarly journals Fe3O4@C Nanoparticles Synthesized by In Situ Solid-Phase Method for Removal of Methylene Blue

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 330
Author(s):  
Hengli Xiang ◽  
Genkuan Ren ◽  
Yanjun Zhong ◽  
Dehua Xu ◽  
Zhiye Zhang ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Solid Phase ◽  
Raw Materials ◽  
Phase Method ◽  
Maximum Adsorption Capacity ◽  
High Catalytic Activity ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
High Concentrations

Fe3O4@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO4, FeS2, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results indicated that the maximum adsorption capacity of the Fe3O4@C nanoparticles was 18.52 mg/g, and that the adsorption process was exothermic. Additionally, by employing H2O2 as the initiator of a Fenton-like reaction, the removal efficiency of 100 mg/L MB reached ~99% with Fe3O4@C nanoparticles, while that of MB was only ~34% using pure Fe3O4 nanoparticles. The mechanism of H2O2 activated on the Fe3O4@C nanoparticles and the possible degradation pathways of MB are discussed. The Fe3O4@C nanoparticles retained high catalytic activity after five usage cycles. This work describes a facile method for producing Fe3O4@C nanoparticles with excellent catalytic reactivity, and therefore, represents a promising approach for the industrial production of Fe3O4@C nanoparticles for the treatment of high concentrations of dyes in wastewater.

Sign in / Sign up

Export Citation Format

Share Document