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.

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.

Non-Alloyed Ohmic Contacts to n-GaAs Using Epitaxial Ge Layers

1985 ◽  
Vol 54 ◽  
Author(s):  
T. Sawada ◽  
W. X. Chen ◽  
E. D. Marshall ◽  
K. L. Kavanagh ◽  
T. F. Kuech ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solid State ◽  
Ohmic Contacts ◽  
Solid Phase ◽  
Solid State Reactions ◽  
Solid Phase Epitaxy ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Shallow Junctions

ABSTRACTAlloyed ohmic contacts (i.e. Au-Ge-Ni) to n-GaAs lead to non-planar interfaces which are unsuitable for devices with shallow junctions and small dimensions. In this study, the fabrication of non-alloyed ohmic contacts (via solid state reactions) is investigated. A layered structure involving the solid phase epitaxy of Ge using a transport medium (PdGe) is shown to produce low (1 — 5 × 10∼6Ω cm2) and reproducible values of contact resistivity. The resultant interface is shown to be abrupt by cross-sectional transmission electron microscopy.

In Situ High-Temperature Transmission Electron Microscopy Observations of the Formation of Nanocrystalline TiC from Nanocrystalline Anatase (TiO2)

1998 ◽  
Vol 4 (3) ◽  
pp. 269-277 ◽  
Author(s):  
A. Agrawal ◽  
J. Cizeron ◽  
V.L. Colvin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Solid Phase ◽  
Anatase Phase ◽  
High Resolution Electron Microscopy ◽  
Rutile Phase ◽  
Transmission Electron ◽  
New Phase

In this work, the high-temperature behavior of nanocrystalline TiO2 is studied using in situ transmission electron microscopy (TEM). These nanoparticles are made using wet chemical techniques that generate the anatase phase of TiO2 with average grain sizes of 6 nm. X-ray diffraction studies of nanophase TiO2 indicate the material undergoes a solid-solid phase transformation to the stable rutile phase between 600° and 900°C. This phase transition is not observed in the TEM samples, which remain anatase up to temperatures as high as 1000°C. Above 1000°C, nanoparticles become mobile on the amorphous carbon grid and by 1300°C, all anatase diffraction is lost and larger (50 nm) single crystals of a new phase are present. This new phase is identified as TiC both from high-resolution electron microscopy after heat treatment and electron diffraction collected during in situ heating experiments. Video images of the particle motion in situ show the nanoparticles diffusing and interacting with the underlying grid material as the reaction from TiO2 to TiC proceeds.

Microstructure of Oxidized Ge0.78SiO.12 annealed in a Reducing Ambient

1995 ◽  
Vol 379 ◽  
Author(s):  
N.D. Theodore ◽  
W.S. Liu ◽  
D.Y.C. Lie ◽  
T.K. Cams ◽  
K.L. Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Seeding Layer ◽  
Transmission Electron ◽  
Microstructural Behavior ◽  
Defect Densities

ABSTRACTTransmission electron microscopy, conventional and high-resolution, is used to characterize the microstructural behavior of oxidized Ge0.78Si0.12 layers annealed in a reducing 95% N2+ 5% H2 ambient. An epitaxial Ge layer grows by solid-phase epitaxy on an underlying Ge0.78Si0.12 seeding layer with a Ge-Sio2 matrix positioned between them. Defect densities in the epitaxial Ge are significantly lower than in the underlying Ge0.78Si0.12. Microstructural details of this behavior are investigated.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

Transmission electron microscopy assessment of the Si enhancement of Ti∕Al∕Ni∕Au Ohmic contacts to undoped AlGaN∕GaN heterostructures

2006 ◽  
Vol 100 (3) ◽  
pp. 034904 ◽  
Author(s):  
Vincent Desmaris ◽  
Jin-Yu Shiu ◽  
Chung-Yu Lu ◽  
Niklas Rorsman ◽  
Herbert Zirath ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ohmic Contacts ◽  
Transmission Electron
Sign in / Sign up

Export Citation Format

Share Document