scholarly journals Influence of Carbon Layer on the Properties of Ni-Based Ohmic Contact to n-Type 4H-SiC

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
A. Kuchuk ◽  
V. Kladko ◽  
Z. Adamus ◽  
M. Wzorek ◽  
M. Borysiewicz ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Carbon Layer ◽  
Specific Contact Resistance ◽  
Interface Quality ◽  
Additional Layer ◽  
Specific Contact ◽  
Lower Temperature ◽  
Interfacial Carbon

Nickel-based contacts with additional interfacial layer of carbon, deposited on n-type 4H-SiC, were annealed at temperatures ranging from 600 to 1000°C and the evolution of the electrical and structural properties were analyzed by I-V measurements, SIMS, TEM, and Raman spectroscopy. Ohmic contact is formed after annealing at 800°C and minimal specific contact resistance of about 2.0×10-4 Ω cm2 has been achieved after annealing at 1000°C. The interfacial carbon is amorphous in as-deposited state and rapidly diffuses and dissolves in nickel forming graphitized carbon. This process activates interfacial reaction between Ni and SiC at lower temperature than usual and causes the formation of ohmic contact at relatively low temperature. However, our results show that the specific contact resistance as well as interface quality of contacts was not improved, if additional layer of carbon is placed between Ni and SiC.

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.

Improved Low Resistance Contacts of Ni/Au and Pd/Au to P-Type GaN Using a Cryogenic Treatment

1999 ◽  
Vol 595 ◽  
Author(s):  
Mi-Ran Park ◽  
Wayne A. Anderson ◽  
Seong-Ju Park
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Cryogenic Treatment ◽  
Microstructural Analysis ◽  
Chemical Vapor ◽  
Specific Contact Resistance ◽  
Mixed Gas ◽  
Low Resistance ◽  
Specific Contact ◽  
P Type

AbstractA low resistance Ohmic contact to p-type GaN is essential for reliable operation of electronic and optoelectronic devices. Such contacts have been made using Ni/Au and Pd / Au contacts to p-type Mg-doped GaN (1.41×1017 cm−3) grown by metalorganic chemical vapor deposition ( MOCVD ) on ( 0001 ) sapphire substrates. Thermal evaporation was used for the deposition of those metals followed by annealing at temperatures of 400 ∼ 700 °C in an oxygen and nitrogen mixed gas ambient, then subsequently cooled in liquid nitrogen which reduced the specific contact resistance from the range of 9.46∼2.80×10−2 ωcm2 to 9.84∼2.65×10−4 ωcm2 for Ni/Au and from the range of 8.35∼5.01×10−4 ωcm2 to 3.34∼1.80×10−4 ωcm2 for Pd/Au. The electrical characteristics for the contacts were examined by the current versus voltage curves and the specific contact resistance was determined by use of the circular transmission line method (c-TLM). The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance will be discussed from a microstructural analysis which reveals the metallurgy of Ohmic contact formation.

NIIN As an Ohmic Contact to P-GAN

1998 ◽  
Vol 537 ◽  
Author(s):  
D. B. Ingerly ◽  
Y. A. Chang ◽  
Y. Chen
Keyword(s):  
Solid State ◽  
Intermetallic Compound ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Schottky Barrier Height ◽  
Rf Sputtering ◽  
Specific Contact Resistance ◽  
Transmission Line Model ◽  
Specific Contact ◽  
Compound Target

AbstractBased on the criteria for the solid state exchange reaction with p-GaN, we have investigated the intermetallic compound Niln as a possible ohmic contact. The contacts were fabricated by depositing Niln on p-GaN films (p ∼ 2 × 1017 cm-3) using RF sputtering from a compound target. The as-deposited, Niun contacts were found to be rectifying and using I-V characterization a Schottky barrier height of 0.82 eV was measured. Rapid thermal annealing of the contacts was shown to significantly decrease their resistance, with contacts annealed at 800°C for I min yielding the lowest resistance. When annealed at 800°C for 1 min Niln contacts exhibited a specific contact resistance of 8-9 × 10-3 Ωcm2, as measured by the circular transmission line model. To allow a more universal comparison the more traditional Ni/Au contacts, processed under the same conditions, were used as a standard. Their measured specific contact resistance (ρc = 1.2 - 2.1 x 10-2 Ωcm2) was significantly higher than that of the Niln contacts. Demonstrating that Niln has promise as an ohmic contact to p-GaN and should be studied in greater detail.

scholarly journals Improved Low Resistance Contacts of Ni/Au and Pd/Au to p-Type GaN Using a Cryogenic Treatment

2000 ◽  
Vol 5 (S1) ◽  
pp. 901-907
Author(s):  
Mi-Ran Park ◽  
Wayne A. Anderson ◽  
Seong-Ju Park
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Cryogenic Treatment ◽  
Microstructural Analysis ◽  
Chemical Vapor ◽  
Specific Contact Resistance ◽  
Mixed Gas ◽  
Low Resistance ◽  
Specific Contact ◽  
P Type

A low resistance Ohmic contact to p-type GaN is essential for reliable operation of electronic and optoelectronic devices. Such contacts have been made using Ni/Au and Pd / Au contacts to p-type Mg-doped GaN (1.41×1017 cm−3) grown by metalorganic chemical vapor deposition ( MOCVD ) on ( 0001 ) sapphire substrates. Thermal evaporation was used for the deposition of those metals followed by annealing at temperatures of 400 ∼ 700 °C in an oxygen and nitrogen mixed gas ambient, then subsequently cooled in liquid nitrogen which reduced the specific contact resistance from the range of 9.46∼2.80×10−2 Ωcm2 to 9.84∼2.65×10−4 Ωcm2 for Ni/Au and from the range of 8.35∼5.01×10−4 Ωcm2 to 3.34∼1.80×10−4 Ωcm2 for Pd/Au. The electrical characteristics for the contacts were examined by the current versus voltage curves and the specific contact resistance was determined by use of the circular transmission line method (c-TLM). The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance will be discussed from a microstructural analysis which reveals the metallurgy of Ohmic contact formation.

Formation of Ni/Pt/Au Ohmic Contacts to p-GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
Ja-Soon Jang ◽  
Hyo-Gun Kim ◽  
Kyung-Hyun Park ◽  
Chang-Sub Um ◽  
Il-Ki Han ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Chemical Vapor ◽  
Electron Beam Evaporation ◽  
Specific Contact Resistance ◽  
Metal Thin Films ◽  
Linear Behavior ◽  
Specific Contact ◽  
P Type

AbstractWe report a new Ni/Pt/Au (20/30/80 nm) metallization scheme to achieve a low ohmic contacts to p-type GaN with a carrier concentration of 9.4 × 1016 cm-3. A Mg-doped GaN layer (0.5 μm) was grown on (0001) sapphire substrate by metalorganic chemical vapor deposition (MOCVD). All metal thin films were deposited on the p-GaN layer in an electron-beam evaporation system. Samples were annealed by a rapid thermal annealing (RTA) process at a range of temperatures from 300 °C to 850 °C under a flowing Ar atmosphere. A circulartransmission line model (c-TLM) was employed to calculate the specific contact resistance, and current-voltage (I-V) data were measured with HP4155A. The Ni/Pt/Au contacts without the annealing process showed nearly rectifying characteristics. The ohmic contacts were formed on the samples annealed at 500 °C for 30 sec and the I-V data showed a linear behavior. The specific contact resistance was 2.1 × 10-2 Ωcm2. However with increasing the annealing temperature above 600 °C, ohmic contacts were again degraded. Auger electron spectroscopy (AES) depth profiles were used to investigate the interfacial reactions between the trilayer and GaN. AES results suggested that Pt plays a significant role in forming ohmic contact as an acceptor at the interface. Atomic force microscope (AFM) also showed that the samples with good ohmic contact have very smooth surface.

scholarly journals Circular test structures for determining the specific contact resistance of ohmic contacts

2017 ◽  
Vol 30 (3) ◽  
pp. 313-326 ◽  
Author(s):  
Anthony Holland ◽  
Yue Pan ◽  
Mohammad Alnassar ◽  
Stanley Luong
Keyword(s):  
Finite Element ◽  
Contact Resistance ◽  
Finite Element Modeling ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Wave Mechanics ◽  
Element Modeling ◽  
Specific Contact ◽  
Modeling Software

Though the transport of charge carriers across a metal-semiconductor ohmic interface is a complex process in the realm of electron wave mechanics, such an interface is practically characterised by its specific contact resistance. Error correction has been a major concern in regard to specific contact resistance test structures and investigations by finite element modeling demonstrate that test structures utilising circular contacts can be more reliable than those designed to have square shaped contacts as test contacts become necessarily smaller. Finite element modeling software NASTRAN can be used effectively for designing and modeling ohmic contact test structures and can be used to show that circular contacts are efficient in minimising error in determining specific contact resistance from such test structures. Full semiconductor modeling software is expensive and for ohmic contact investigations is not required when the approach used is to investigate test structures considering the ohmic interface as effectively resistive.

The Effect of Chemical Treatment of the GaAs Surface on the Ohmic Contact Properties

1990 ◽  
Vol 181 ◽  
Author(s):  
Balázs Kovács ◽  
Margit Németh-Sallay ◽  
Imre Mojzes
Keyword(s):  
Contact Resistance ◽  
Epitaxial Layer ◽  
Ohmic Contact ◽  
Chemical Treatment ◽  
Surface Condition ◽  
Gaas Surface ◽  
Specific Contact Resistance ◽  
Native Oxide Layer ◽  
Specific Contact ◽  
Gaas Epitaxial Layer

ABSTRACTElectrical properties of metal/GaAs system are known to be influenced very much by GaAs surface condition before the metal deposition. The surface condition of GaAs epitaxial layer can be affected by the wet chemical treatment of the surface. The influence of different processes were compared to choose the best technique for a high quality ohmic contact technology. Applying a chemical treatment which contains degreasing process, a light surface etching and a rinsing process, the carbon contaminations, 20-25 nm GaAs surface layer and the native oxide layer are removed from the GaAs surface. The benefit of the rinsing step is to produce a reproducible, stable surface condition before the metallization. Since the importance of the finishing step was assumed, the investigated processes differed in this step. The compared methods finished with either alkaline, like NH4OH, or acidic, like HCl, etchants resulted higher specific contact resistance than the process finished with neutral, high purity (18 MΩcm) water. In the latest case the obtained specific contact resistance was (6.4 ± 2.7) ×10−6 Ωcm2 on a GaAs epitaxial layer with the doping concentration 1.5 × 1017cm−3.

scholarly journals Reliable Ohmic Contact Properties for Ni/Hydrogen-Terminated Diamond at Annealing Temperature up to 900 °C

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 470
Author(s):  
Xiaolu Yuan ◽  
Jiangwei Liu ◽  
Jinlong Liu ◽  
Junjun Wei ◽  
Bo Da ◽  
...  
Keyword(s):  
Ohmic Contact ◽  
Annealing Temperature ◽  
Electronic Devices ◽  
Schottky Contacts ◽  
Specific Contact Resistance ◽  
Annealing Temperatures ◽  
Current Voltage ◽  
Specific Contact ◽  
Contact Electrode

Ohmic contact with high thermal stability is essential to promote hydrogen-terminated diamond (H-diamond) electronic devices for high-temperature applications. Here, the ohmic contact characteristics of Ni/H-diamond at annealing temperatures up to 900 °C are investigated. The measured current–voltage curves and deduced specific contact resistance (ρC) are used to evaluate the quality of the contact properties. Schottky contacts are formed for the as-received and 300 °C-annealed Ni/H-diamonds. When the annealing temperature is increased to 500 °C, the ohmic contact properties are formed with the ρC of 1.5 × 10−3 Ω·cm2 for the Ni/H-diamond. As the annealing temperature rises to 900 °C, the ρC is determined to be as low as 6.0 × 10−5 Ω·cm2. It is believed that the formation of Ni-related carbides at the Ni/H-diamond interface promotes the decrease in ρC. The Ni metal is extremely promising to be used as the ohmic contact electrode for the H-diamond-based electronic devices at temperature up to 900 °C.

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