Microstructural analysis of NiInGe ohmic contacts for n-type GaAs

2002 ◽  
Vol 31 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Yukito Tsunoda ◽  
Masanori Murakami
Keyword(s):  
Ohmic Contacts ◽  
Microstructural Analysis

Microstructural Analysis of Ti/Ni Bilayer Ohmic Contacts on 4H-SiC Layers

2019 ◽  
Vol 963 ◽  
pp. 494-497
Author(s):  
Vinoth Kumar Sundaramoorthy ◽  
Lukas Kranz ◽  
Giovanni Alfieri
Keyword(s):  
Structural Analysis ◽  
Diffraction Pattern ◽  
Ohmic Contacts ◽  
Microstructural Analysis ◽  
Carbon Segregation ◽  
Film Interface

The micro-structural analysis of Ti/Ni bilayer as Ohmic contacts to n-type 4H-SiC is reported. There was no carbon segregation at the interface between the NiSi layer and the 4H-SiC layer for Ti/Ni contacts, unlike pure Ni contacts. The diffraction pattern image shows the presence of the cubic NiSi film which grows on the SiC surface. The film interface with the SiC was uniform and more planar. An optimized contact in terms of contact morphology was achieved using a bilayer contact Ti/Ni (20/100nm) annealed at 1100 °C for 5 minutes in vacuum.

Microstructure and Temperature Dependent Electrical Characteristics of Ohmic Contacts to AlGaN/GaN Heterostructures

2015 ◽  
Vol 821-823 ◽  
pp. 999-1002
Author(s):  
Giuseppe Greco ◽  
Ferdinando Iucolano ◽  
Fabrizio Roccaforte
Keyword(s):  
Ohmic Contacts ◽  
Microstructural Analysis ◽  
Specific Contact Resistance ◽  
Interfacial Region ◽  
Temperature Dependent ◽  
Scientific Debate ◽  
Specific Contact ◽  
Thermionic Field Emission ◽  
High Frequency Devices ◽  
Dimensional Electron Gas

AlGaN/GaN heterostructures are important materials for the fabrication of high power and high frequency devices. However, the mechanisms of Ohmic contacts formation on these systems are continuously under scientific debate. In this paper, a structural and electrical investigation of Ti/Al/Ni/Au Ohmic contacts to AlGaN/GaN heterostructures is reported. In particular, the behavior of Ti/Al/Ni/Au multilayers was monitored at different annealing temperatures. The contacts became Ohmic after annealing at 750°C and showed a decreasing temperature behavior of the specific contact resistanceRC, described by a thermionic field emission mechanism. On the other hand, annealing at 850°C led to a further reduction ofRC, with a slightly increasing dependence ofRCon the measurement temperature (here regarded as a “metal-like” behavior). The microstructural analysis of the interfacial region allowed to explain the results with the formation of metallic intrusions contacting directly the two dimensional electron gas.

Microstructural analysis of Ti/Al/Ti/Au ohmic contacts ton-AlGaN/GaN

2002 ◽  
Vol 20 (3) ◽  
pp. 1004-1010 ◽  
Author(s):  
J. Chen ◽  
D. G. Ivey ◽  
J. Bardwell ◽  
Y. Liu ◽  
H. Tang ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Microstructural Analysis

RTA-Treated Ohmic Contacts To GaAs Containing WSiN Barriers

1995 ◽  
Vol 387 ◽  
Author(s):  
E. Nebauer ◽  
U. Merkel ◽  
J. Würfl ◽  
W. Österle
Keyword(s):  
Ohmic Contacts ◽  
Microstructural Analysis ◽  
Depth Profiling ◽  
Electron Beam Evaporation ◽  
Contact System ◽  
Halogen Lamp ◽  
Secondary Phases ◽  
Semiconductor Interface ◽  
Multilayered Systems ◽  
Short Time

AbstractFor III-V device operation at 300 °C or above ohmic contacts have to consist of multilayered systems comprising an amorphous diffusion barrier. The contact system Au/Pt/Ti/WSiN/ Au/Ge/Ni-n-GaAs (n ≈ 5.1017 cm−3) has been developed and optimized with respect to the parameters of the barrier as well as the internal Au/Ge/Ni layers. The WSiN layer was deposited via reactive dc magnetron sputtering, the other layers by electron beam evaporation without breaking the vacuum. Annealing has been performed in a halogen lamp furnace. The contact resistance Rc as determined by TLM structures was measured as function of the annealing temperature and time. It was found that short-time annealings lead to a broad Rc minimum at 0.1 ωmm. For such Rc's the Au/Ge/Ni layer thicknesses must be ≥ 20/10/6 nm. Extended microstructural analysis was accomplished by XTEM/EDS and by AES and SNMS depth profiling. The typical alloying depth of the contact in the GaAs has been found to be about 50 nm, i.e. smaller than for the conventional Au/Ni/AuGe contact. The secondary phases formed (Au(Ga), NiGe(As)) are similar. With annealing conditions producing the desired Rc value, both Au(Ga) and NiGe(As) were observed in a bamboo-like arrangement at the metal-semiconductor interface. Degradation of Rc could be attributed to burying of the nickel-rich phases beneath gold-rich phases. This contact system is stable up to ≈ 300°C.

scholarly journals Microstructural Analysis at Metal/Semiconductor Interface for Ideal Ohmic Contacts

Materia Japan ◽  
1998 ◽  
Vol 37 (12) ◽  
pp. 998-998
Author(s):  
Masanori Murakami ◽  
Yasuo Koide ◽  
Takeo Oku
Keyword(s):  
Ohmic Contacts ◽  
Microstructural Analysis ◽  
Semiconductor Interface

Microstructural analysis of Pd-based ohmic contacts to p-type GaAs

1991 ◽  
Vol 6 (3) ◽  
pp. 553-559 ◽  
Author(s):  
K.M. Schmitz ◽  
K.L. Jiao ◽  
R. Sharma ◽  
W.A. Anderson ◽  
G. Rajeswaran ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Broad Band ◽  
Microstructural Analysis ◽  
Composition Profile ◽  
Electrical Measurements ◽  
Cross Sectional ◽  
Transmission Electron ◽  
P Type ◽  
Ohmic Contact Formation ◽  
Secondary Ion

As part of the investigation of the use of Pd-based ohmic contacts to p-type GaAs, cross-sectional transmission electron microscopy, Auger electron spectroscopy, and secondary ion mass spectroscopy were used to explore the uniformity at the metal/GaAs interface and its composition profile after ohmic contact formation. Comparisons were made among Au:Be, Au:Be/Pd, and Au/Pd contacts. Regions of p+ were formed in n-type GaAs by a spin-on source which was rapid diffused at 950 °C for 6 s or by ion implantation at a dose of 3 × 1014 atoms/cm2 at 150 keV for 15 min. Metallizations were accomplished by evaporation with a base pressure of 3 × 10−6 Torr. Sintering of the metallizations was done in a furnace at 350 °C for 15 min. Cross-sectional transmission electron microscope studies revealed an absence of spiking when Be is present in the metallization scheme but a broad band diffused into GaAs. An improper metal/GaAs adhesion was observed when Pd is absent. Be assists in confining the reaction of Pd with GaAs and acts as a diffusion barrier to the p+ dopant. Electrical measurements, taken from transmission line and cross bridge Kelvin resistors, were best for the Pd/Au:Be, which yielded a contact resistance of 0.3 μΩ-cm2.

Microstructural Analysis of SiO2-Al2O3 Glasses

1982 ◽  
Vol 40 ◽  
pp. 562-563
Author(s):  
C. M. Jantzen ◽  
D. G. Howitt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microstructural Analysis ◽  
Liquid Immiscibility ◽  
Metastable Region ◽  
Transmission Electron ◽  
Liquidus Temperatures

The mullite-SiO2 liquidus has been extensively studied, and it has been shown that the flattening of the liquidus is related to the existence of a metastable region of liquid immiscibility at sub-liquidus temperatures which is detectable by transmission electron microscopy (TEM) (Fig. 1).

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

1987 ◽  
Vol 45 ◽  
pp. 326-327
Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Microstructural Characterization ◽  
Almost Everywhere ◽  
Spacer Layer ◽  
Good Contact ◽  
The Relationship ◽  
Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

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