Correlation Between the Microstructures and the Electrical Properties of Ni/Au/Te/Au Contacts on n-GaAs

1994 ◽  
Vol 337 ◽  
Author(s):  
X. W. Lin ◽  
J. Watté ◽  
K. Wuyts ◽  
W. Swider ◽  
R.E. Silverans ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrical Properties ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Structural Evolution ◽  
Reaction Products ◽  
Transmission Electron ◽  
Major Reaction ◽  
Ohmic Contact Formation

ABSTRACTThe structural evolution of Ni/Au/Te/Au contacts on n-GaAs (001) was examined, in correlation with their electrical properties as a function of rapid thermal annealing in the temperature range 350 - 600°C. It was found that heating at temperatures ≥ 550°C results in the formation of ohmic contacts, while contacts annealed at lower temperatures remain nonohmic. Transmission electron microscopy revealed that heating ≥ 450°C leads to extensive reactions between Ni/Au/Te/Au and GaAs and deep spike formation into the GaAs. The major reaction products were identified as NiAs and β-AuGa. Ga2Te3 grains, growing epitaxially on GaAs, were detected only in 550°C annealed samples. Heating to 600°C caused considerable Ga2Te3 loss. Implications of these results concerning the ohmic contact formation mechanism are discussed.

Metallurgical and Electrical Properties of Capped Au-based Metallizations on GaAs

1993 ◽  
Vol 300 ◽  
Author(s):  
X. W. Lin ◽  
A. Piotrowska ◽  
E. Kaminska ◽  
Z. Liliental-Weber ◽  
J. Washburn
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Ohmic Contact ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flat Interface ◽  
Transmission Electron ◽  
Current Voltage ◽  
Ohmic Contact Formation ◽  
Electrical Data

ABSTRACTGold-based contacts on GaAs, i.e., Au(Te)/n-GaAs, Au(Ge)/n-GaAs, and Au(Zn)/p- GaAs, were annealed with or without an Al2O3 cap, in order to examine the effects of capping on their metallurgical and electrical properties. Current-voltage measurements showed that ohmic contact can be formed for all the metallizations, except capped Au(Te) which remained nonohmic even after annealing up to 480°C. Transmission electron microscopy and x-ray diffraction observations showed that the reactions between a contact and GaAs can be strongly affected by a capping layer. For all uncapped contacts, annealing generally resulted in growth of Au-Ga compounds and nonuniform contact morphology, whereas capped Au(Ge) and Au(Zn) contacts were stable and retained flat interface with GaAs. Capped Au(Te) was found to be unstable, reacting extensively with GaAs, due to the presence of Te. Electrical data are explained in terms of the doping model for ohmic contact formation.

Microtexture of shock reaction products of niobium and silica mixtures

1999 ◽  
Vol 14 (7) ◽  
pp. 3169-3174 ◽  
Author(s):  
Reiko Murao ◽  
Masae Kikuchi ◽  
Kiyoto Fukuoka ◽  
Eiji Aoyagi ◽  
Toshiyuki Atou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Shock Compression ◽  
Pressure Range ◽  
Reaction Products ◽  
Small Particles ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron

Shock compression experiments on powder mixtures of niobium metal and quartz were conducted for the pressure range of 30–40 GPa by a 25-mm single-stage propellant gun. Chemical reaction occurred above 35 GPa, and products were found to be mainly so-called “Cu3Au-type” Nb3Si, which contained a small amount of oxygen. Microtextures of the specimen were examined by scanning and transmission electron microscopy. A field-emission transmission electron microscope was used for energy-dispersive x-ray analysis of microtextures in small particles found in the SiO2 matrix, and various species with different Nb/Si ratio and oxygen content were shown to be produced through the nonequilibrium process of shock compression.

Electron microscopy study of interfacial structure and reaction of Yba2Cu3O7/Y-ZrO2 films on LaAlO3 substrates

1998 ◽  
Vol 13 (6) ◽  
pp. 1485-1491 ◽  
Author(s):  
J. Y. Dai ◽  
F. H. Kaatz ◽  
P. R. Markworth ◽  
D. B. Buchholz ◽  
X. Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Interfacial Reaction ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Interfacial Structure ◽  
Reaction Products ◽  
Transmission Electron

The detailed structure and interfacial reaction of epitaxial Yba2Cu3O7/Y-ZrO2 (YBCO/YSZ) films grown by chemical vapor deposition (CVD) on LaAlO3 (LAO) substrates are investigated by means of high-resolution electron microscopy (HREM), analytical transmission electron microscopy, and scanning transmission electron microscopy (STEM). The epitaxial relations of YBCO/YSZ/LAO are [100]YBCO // [110]YSZ // [100]LAO and (001)YBCO // (001)YSZ // (001)LAO. The optimum atomic configuration at the YSZ/LAO interface, in which oxygen is the first atomic layer on LAO, is proposed by using HREM combined with image simulation based on the atomic structure models of the interface. Near the YBCO/YSZ interface, two localized interfacial reaction products are formed: (i) a Y-rich modulated ZrO2 structure at the surface of the YSZ film, which may be caused by the diffusion of Y into the YSZ grains; (ii) an intergranular BaZrO3 phase formed by the diffusion of Ba along the columnar grain boundaries of the YSZ film during YBCO growth.

An Approach to Improving the Morphology and Reliability of n-SiC Ohmic Contacts to SiC Using Second-Metal Contacts

2006 ◽  
Vol 527-529 ◽  
pp. 859-862 ◽  
Author(s):  
Matthew H. Ervin ◽  
Kenneth A. Jones ◽  
Un Chul Lee ◽  
Taniya Das ◽  
M.C. Wood
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Chemical Properties ◽  
Physical Contact ◽  
Metal Contacts ◽  
Critical Feature ◽  
Excess Carbon ◽  
Ohmic Contact Formation

While nickel ohmic contacts to n-type silicon carbide have good electrical properties, the physical contact, and therefore the reliability, can be poor. An approach is described for using the good electrical properties of Ni ohmic contacts while using another metal for its desired mechanical, thermal and/or chemical properties. In the present work, once the Ni contacts have been annealed forming nickel silicides and achieving low contact resistance, they are etched off. Removing the primary Ni contacts also eliminates the poor morphology, voids, and at least some of the excess carbon produced by the Ni/SiC reaction. The Ni contacts are then replaced by a second contact metal. This second metal displays low contact resistance as-deposited, indicating that the critical feature responsible for the ohmic contact has not been removed by the primary contact etch. Not only does this approach provide more flexibility for optimizing the contact for a given application, it also provides some insight into the ohmic contact formation mechanism.

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

Microstructure Analysis of Thermally Stable Ohmic Contact to Both n and p+-GaAs

1992 ◽  
Vol 281 ◽  
Author(s):  
W. Y. Han ◽  
H. S. Lee ◽  
Y. Lu ◽  
M. W. Cole ◽  
L. M. Casas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ohmic Contact ◽  
Auger Electron ◽  
Specific Contact Resistance ◽  
Thermally Stable ◽  
Depth Profiles ◽  
Transmission Electron ◽  
Specific Contact ◽  
Electron Spectrometry

ABSTRACTA thermally stable Pd/Ge/Ti/Pt/ ohmic contact with low specific contact resistance was formed on both n and p+-GaAs. The lowest specific contact resistances were 4.7×10−7 and 6.4×10−7 Ω.cm2 for the n and p+-GaAs, respectively, when the n-GaAs was doped with Si to 2×1018cm−3, and the p+-GaAs was doped with carbon to 5×1019 cm−3. Interfacial reactions and element diffusions of the contacts were investigated by using transmission electron microscopy, Auger electron spectrometry with depth profiles. All the contacts were thermally stable at 300 °C for 20 hours, and it appeared that the p-contacts were more stable than the n-contacts.

A structural analysis of the Pd/GaN ohmic contact annealing behavior

2002 ◽  
Vol 743 ◽  
Author(s):  
C. C. Kim ◽  
P. Ruterana ◽  
J. H. Je
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Structural Evolution ◽  
Electron Beam Evaporation ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Annealing Behavior ◽  
X Ray ◽  
Transmission Electron ◽  
The Relationship

AbstractFor ohmic contact on p GaN, palladium is one of the best candidates showing ohmic characteristics already without annealing. To be realized in devices, it is necessary to know the behavior of the ohmic contacts at accelerated conditions, especially for high temperatures and power. We report on the structural evolution of palladium layers (30 nm) deposited on GaN (0001) by electron beam evaporation without intentional annealing. They were next cut into various pieces which were individually submitted to rapid thermal annealing at 400, 500, 600, 700 and 800°C for 10 sec. We investigate the differences in the microstructure and the location of interfacial phases and their relationships as determined by X-ray diffraction and transmission electron microscopy, we then suggest the formation mechanism based on the relationship. It is shown that the interface is disrupted at annealing above 600°C and by 800°C only very small patches of Pd are still present, however they area completely imbedded in a matrix of intermetallic phases (gallides) formed by the reaction with GaN.

Chemistry, microstructure, and electrical properties at interfaces between thin films of cobalt and alpha (6H) silicon carbide (0001)

1995 ◽  
Vol 10 (1) ◽  
pp. 26-33 ◽  
Author(s):  
L.M. Porter ◽  
R.F. Davis ◽  
J.S. Bow ◽  
M.J. Kim ◽  
R.W. Carpenter
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Electrical Properties ◽  
Photoelectron Spectroscopy ◽  
Electron Beam Evaporation ◽  
Leakage Currents ◽  
X Ray ◽  
Transmission Electron

Thin films (4–1000 Å) of Co were deposited onto n-type 6H-SiC(0001) wafers by UHV electron beam evaporation. The chemistry, microstructure, and electrical properties were determined using x-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and I-V and C-V measurements, respectively. The as-deposited contacts exhibited excellent rectifying behavior with low ideality factors and leakage currents of n < 1.06 and 2.0 × 10−8 A/cm2 at −10 V, respectively. During annealing at 1000 °C for 2 min, significant reaction occurred resulting in the formation of CoSi and graphite. These annealed contacts exhibited ohmic-like character, which is believed to be due to defects created in the interface region.

Sign in / Sign up

Export Citation Format

Share Document