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.

Laser annealed ohmic contact to n+-GaAs

1983 ◽  
Vol 61 (8) ◽  
pp. 1218-1221 ◽  
Author(s):  
P. Sircar
Keyword(s):  
Surface Morphology ◽  
Contact Resistance ◽  
Excimer Laser ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Laser Annealing ◽  
Furnace Annealing ◽  
Gaas Substrates ◽  
Thin Nickel ◽  
Lower Contact

Ohmic contacts were made on n+-GaAs substrates by evaporating a gold–germanium eutectic film with or without a thin nickel overlayer and then alloying these samples either in a furnace or by means of an excimer laser. It is found that laser annealing gives a better surface morphology and a lower contact resistance than furnace annealing.

Characterization of Sputtered Ge Film

1994 ◽  
Vol 343 ◽  
Author(s):  
Jaeshin Cho ◽  
N. David Theodore
Keyword(s):  
Electrical Resistivity ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Amorphous Structure ◽  
Sharp Transition ◽  
Germanium Film ◽  
Contact Property ◽  
Anneal Temperature

ABSTRACTThe electrical resistivity and microstructure of sputtered germanium film were characterized as a function of anneal temperature from 400 to 700°C. The as-deposited sputtered Ge film had an amorphous structure with resistivity of 165 Ω-cm which was maintained after annealing up to 540°C. After annealing above 550°C, the resistivity dropped by almost four orders of magnitude to ∼0.027 Ω-cm. The sharp transition of resistivity at 550°C is believed to be due to the recrystallization of Ge film from the as-deposited amorphous structure. The ohmic contact property on Ge films was also evaluated using sputtered tungsten. Low resistance ohmic contacts were obtained both on as-deposited and annealed Ge films, with typical ohmic contact resistance of 0.05 ± 0.008 Ω-mm on annealed Ge films. The W contacts were thermally stable after annealing up to 650°C.

Optimizing n+ Ohmic Contacts on GaAs for HemtS

1992 ◽  
Vol 260 ◽  
Author(s):  
H. M. Harris ◽  
J. R. Farley
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
High Performance ◽  
Ohmic Contacts ◽  
Layer Structure ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
Alloy Process ◽  
Spacer Layer ◽  
Better Than

ABSTRACTLow ohmic contact resistance is essential for high performance microwave and millimeter wave transistors. Rapid thermal processing (RTP) has been used to optimize the ohmic contact resistance of gold - germanium / nickel / gold metallizations on gallium arsenide (GaAs) layers for high electron mobility transistor (HEMT) applications. A HEMT layer structure consisting of a 9000Å buffer layer grown on a semi-insulating substrate followed by a 20Å undoped AlGaAs spacer layer, a 700Å Al0.22Ga0.78 As layer doped at 1.0 × 1018cm-3and a 500Å GaAs cap layer doped at 1.5 × 1018 cm°C to 450°C. Time at temperature was varied from 10 seconds to 1 minute. Optimum conditions for our equipment and layer structure were found to be 365°C for 30 seconds. These conditions produced contact resistances of 0.08 ohm-mm (approximately 2.0 times better than the standard furnace alloy process).

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.

The Relationship Between Microstructure and Contact Resistance in NiAuGe/ZrB2/Au Ohmic Contacts to GaAs.

1990 ◽  
Vol 181 ◽  
Author(s):  
M. P. Grimshaw ◽  
A. E. Staton-Bevan ◽  
J. Herniman ◽  
D. A. Allan
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Gaas Layer ◽  
Contact System ◽  
Initial Contact ◽  
The Relationship ◽  
Resistance Data

ABSTRACTThe microstructure and contact resistance of NiAuGe contacts to n-type GaAs were determined as a function of initial contact composition. The contact microstructures were found to contain varying amounts of of α, α’ and β (or Au7Ga2) Au-Ga, epitaxial Ge, NiGe and NiGeAs phases. A previously unidentified NiAsx (Zr,B) phase was also observed. The contact resistance was found to vary between 0.22-0.38±0.03Ωmm. Comparison of the microstructural and contact resistance data revealed that the ohmic formation models based on (i) the formation of a recrystallised n+ GaAs layer and (ii) the presence of a graded Ge/GaAs heterojunction were not applicable to this contact system.

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.

Ohmic Contact Resistance to GaN Devices Dependence with on Temperature for GaN Devices T

2011 ◽  
Vol 679-680 ◽  
pp. 816-819 ◽  
Author(s):  
Amador Pérez-Tomás ◽  
A. Fontserè ◽  
Marcel Placidi ◽  
N. Baron ◽  
Sébastien Chenot ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Temperature Dependence ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Schottky Diodes ◽  
Electron Gas ◽  
Temperature Measurements ◽  
Back Contact ◽  
Dimensional Electron ◽  
Dimensional Electron Gas

The temperature dependence of Ohmic contacts to GaN devices is investigated in this paper via by measuring TLM contact resistances TLM vs Tas a function of temperature. measurements. In particular, the two types of Ohmic contacts are considered: (1) Contacts to highly doped implanted regions (such as the MOSFET drain/source contacts or the back contact of Schottky diodes) and (2) contacts to the 2 dimensional electron gas (2DEG) of an AlGaN/GaN heterojunction.

Refinement of low-resistance Ni–Ge–Au ohmic contacts to n+ GaAs using screening and response surface experiments

1996 ◽  
Vol 11 (5) ◽  
pp. 1238-1243 ◽  
Author(s):  
Nancy E. Lumpkin ◽  
Warren King ◽  
T. L. Tansley
Keyword(s):  
Contact Resistance ◽  
Response Surface ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
High Electron Mobility Transistors ◽  
Process Variable ◽  
Fractional Factorial ◽  
Order Effects ◽  
High Electron ◽  
Screening Experiment

Multivariable screening and response surface experiments have been performed to model ohmic contact resistance (Rc) of a Ni–Ge–Au ohmic metal process for n+ GaAs-based high electron mobility transistors (HEMTs). Seven variables were examined via a fractional factorial screening experiment to rank the effects of each process variable. The results of the screening experiment indicated that the most significant variables were total Ge and Au evaporated thickness, Ge-to-Au ratio, and the post-alloy cooling time. Response surface experiments were designed around these three variables to examine the first- and second-order effects. The results enabled the development of an empirical model of ohmic contact resistance from which a new low value of 0.03 ± 0.03 Ω · mm (one-sigma) was predicted. Twenty confirmation runs on the new process indicated an average Rc of 0.06 ± 0.02 Ω · mm (one-sigma), with a range of 0.02 Ω · mm to 0.11 Ω · mm, a reduction from the previous average process value of 0.14 ± 0.07 Ω · mm (one-sigma).

Dual Role of Tin Reaction Barrier in Gold-Based Metallization to GaAs

1993 ◽  
Vol 300 ◽  
Author(s):  
A. Piotrowska ◽  
E. Kaminska ◽  
M. Guziewicz ◽  
S. Kwiatkowski ◽  
A. Turos
Keyword(s):  
Magnetron Sputtering ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Diffusion Barrier ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Tin Films ◽  
Specific Contact ◽  
Tin Diffusion Barrier

ABSTRACTThe formation of ohmic contacts to p-GaAs based on Au-Zn system comprising a TiN diffusion barrier has been investigated using 2 MeV He+ RBS and the specific contact resistance measurements. It has been proved that TiN films deposited by reactive RF bias magnetron sputtering serves two purposes. First it suppresses the arsenic evaporation and thus confines the reaction between AuZn and GaAs. Second, it prevents intermixing between p-GaAs/Au(Zn) ohmic contact and an overlayer of Au.

scholarly journals Омические контакты к эпитаксиальным структурам CVD-алмаза с дельта-слоями бора

2019 ◽  
Vol 53 (10) ◽  
pp. 1386
Author(s):  
Е.А. Архипова ◽  
Е.В. Демидов ◽  
М.Н. Дроздов ◽  
С.А. Краев ◽  
В.И. Шашкин ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Diamond Film ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Current Flow ◽  
Cvd Diamond ◽  
Boron Doped ◽  
Heavily Doped ◽  
Test Cells

Various methods of the formation of ohmic contacts to CVD diamond epitaxial structures with boron doped delta layers (δ-layers) are investigated. In the first approach, an additional thin, heavily doped layer was formed on the surface of the diamond film, to which the ohmic contact was formed. Then, the surface p+-layer between the contact pads was etched out, so the current flow in the structure occurred only through the buried δ-layer. In the second approach, doped diamond was selectively grown in contact windows under the mask of metal after preliminary etching the undoped diamond layer (cap) to the δ-layer. In this case, the heavily doped p+-layer will form a contact to the δ-layer. These approaches are differs by conditions of applicability, the complexity of manufacturing technology, the value of contact resistance. So they can be used to solve tasks in which different quality of contacts is required, such as the formation of transistor structures or test cells for measuring electrophysical characteristics.

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