Electrical Property Study of Ni/Nb Contact to n-Type 4H-SiC

2018 ◽  
Vol 924 ◽  
pp. 405-408
Author(s):  
Xue Chao Liu ◽  
Shi Yi Zhuo ◽  
Wei Bin Chen ◽  
Chong Chong Dai ◽  
Er Wei Shi
Keyword(s):  
Electrical Property ◽  
Ohmic Contact ◽  
Sandwich Structure ◽  
Annealing Temperature ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Line Method ◽  
Specific Contact ◽  
Contact Mechanism

A sandwich structure of Ni/Nb/4H-SiC was prepared and annealed at different temperature from 750°C to 1050°C. The electrical property and crystalline structure of Ni/Nb electrode was characterized by transmission line method and X-ray diffraction. It was found that the annealing temperature and the thickness of Ni/Nb layer played an important role in obtaining Ohmic contact. A low specific contact resistance of 1.1×10-5Ω·cm2was obtained when the Ni(50nm)/Nb(50nm) electrode was annealed at 1050°C. The Ohmic contact mechanism of Ni/Nb/4H-SiC was proposed.

Alloying Behavior and Reliabilty of Pt Embedded Metal/n+-GaAs Thin Ohmic Contact System

1996 ◽  
Vol 448 ◽  
Author(s):  
C.Y. Kim ◽  
W.S. Lee ◽  
H.J. Kwon ◽  
Y.W. Jeong ◽  
J.S. Lee ◽  
...  
Keyword(s):  
Ohmic Contact ◽  
Integrated Circuit ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Monolithic Microwave Integrated Circuit ◽  
Surface And Interface ◽  
Transmission Line Method ◽  
Specific Contact

AbstractPt embedded ohmic contacts to n+-GaAs (AuGe-800 Å/ Ni-150 Å/Pt-200 Å/Au-500 Å and AuGe-800 Å/Pt-200 Å/Ni-150 Å/Au-500 Å/n+-GaAs) have been developed for the advanced discrete devices and MMIC (monolithic microwave integrated circuit) applications. The specific contact resistance investigated by Transmission Line Method is 1x10-6 Ω cm2. Ohmic contact reliability investigated by thermal storage test at 300 °C under N2 ambient demonstrated nearly the same contact characteristics after 3000 hours. In both systems, X-ray diffraction results and Auger depth profiles show that the good ohmic contact is related to the formation of Au7Ga2, PtAs2, and Ni19Gen12 phases. AuGa compound enhances the creation of Ga vacancies, allowing incorporation of Ge into Ga sites, and PtAs compound is piled up in the middle of AuGa layer to suppress As outdifrusion from GaAs substrate. TEM cross-sectional view indicates that metal/n+-GaAs reaction layer is ∼ 1200 Å beneath GaAs. Surface and interface are very smooth and abrupt in comparison to conventional AuGe/Ni/Au contact.

Effect of Au distribution in NiO/Au film on the ohmic contact formation to p-type GaN

2005 ◽  
Vol 20 (2) ◽  
pp. 456-463 ◽  
Author(s):  
Jiin-Long Yang ◽  
J.S. Chen ◽  
S.J. Chang
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contact ◽  
Incident Angle ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
Specific Contact ◽  
P Type

The distribution of Au and NiO in NiO/Au ohmic contact on p-type GaN was investigated in this work. Au (5 nm) films were deposited on p-GaN substrates by magnetron sputtering. Some of the Au films were preheated in N2 ambient to agglomerate into semi-connected structure (abbreviated by agg-Au); others were not preheated and remained the continuous (abbreviated by cont-Au). A NiO film (5 nm) was deposited on both types of samples, and all samples were subsequently annealed in N2 ambient at the temperatures ranging from 100 to 500 °C. The surface morphology, phases, and cross-sectional microstructure were investigated by scanning electron microscopy, glancing incident angle x-ray diffraction, and transmission electron microscopy. I-V measurement on the contacts indicates that only the 400 °C annealed NiO/cont-Au/p-GaN sample exhibits ohmic behavior and its specific contact resistance (ρc) is 8.93 × 10−3 Ω cm2. After annealing, Au and NiO contact to GaN individually in the NiO/agg-Au/p-GaN system while the Au and NiO layers become tangled in the NiO/cont-Au/p-GaN system. As a result, the highly tangled NiO-Au structure shall be the key to achieve the ohmic behavior for NiO/cont-Au/p-GaN system.

Dependence of the Au/Ni/Si/Ni Contact Properties on the Si-layer Thickness and the Annealing Temperature in p-type GaN Epilayers

2002 ◽  
Vol 17 (5) ◽  
pp. 1019-1023 ◽  
Author(s):  
S.J. Yang ◽  
T.W. Kang ◽  
T.W. Kim ◽  
K.S. Chung
Keyword(s):  
Layer Thickness ◽  
Annealing Temperature ◽  
Electron Beam Evaporation ◽  
Nitrogen Atmosphere ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Specific Contact ◽  
Potential Applications ◽  
Increasing Temperature ◽  
P Type

The dependences of the properties of Au/Ni/Si/Ni contacts, deposited on p-GaN epilayers by using electron-beam evaporation, on the Si layer thickness and the annealing temperature were investigated with the goal of producing contacts with low specific resistances. The results of the current–voltage (I–V) curves showed that the lowest specific contact resistance obtained for the Au/Ni/Si/Ni contact with a 1200-Å- thick Si layer on p-type GaN annealed at 700 °C for 1 min in a nitrogen atmosphere was 8.49 × 10-4 Ω cm2. The x-ray diffraction (XRD) measurements on the annealed Au/Ni/Si/Ni/p-GaN/sapphire heterostructure showed that Ni3Si, GaAu, and NiGa layers were formed at the Au/Ni/Si/Ni/p-GaN interfaces. While the intensities corresponding to the Ni3Si layer decreased with increasing annealing temperature above 700 °C, those related to the GaAu and the NiGa layers increased with increasing temperature. These results indicate that the Au/Ni/Si/Ni contacts with 1200-Å-thick Si layers annealed at 700 °C hold promise for potential applications in p-GaN-based optoelectronic devices.

Low Resistance Ohmic Contacts Formation and Mechanism of Current Transport Through p-GaN and p-AlGaN

2008 ◽  
Vol 1108 ◽  
Author(s):  
Indra Chary ◽  
Boris Borisov ◽  
Vladimir Kuryatkov ◽  
Yuriy Kudryavtsev ◽  
R Asomoza ◽  
...  
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Hole Concentration ◽  
Specific Contact Resistance ◽  
Current Transport ◽  
Bilayer Thickness ◽  
Aluminum Oxides ◽  
Mg Doping ◽  
Specific Contact

AbstractWe report the influence of surface treatment, annealing temperature and metal bilayer thickness on the specific contact resistance (ρc) of Au/Ni ohmic contacts to p-GaN and p-AlGaN. Ohmic contact on p-GaN with a hole concentration of 6.5 x 1017 cm-3, shows the lowest ρc of ˜9.2 x 10-6 Ω cm2, when GaN was treated in HCl:H2O (3:1) solution before metal deposition and annealed at 500°C for 10 minutes in 90% N2 and 0% O2 atmosphere. Similar procedure applied on p-AlxGa1-xN (x = 5-7%), with a hole concentration of 2.3 x 1017 cm-3, yields a ρc of 1.8 x 10-4 Ω cm2. An increase is observed in ρc when Mg doping exceeds 4 x 1019 cm-3 in both p-GaN and p-AlGaN. This is attributed to Mg self compensation. This increase is more pronounced in AlGaN which we attribute to the presence of residual native aluminum oxides.

scholarly journals Interfacial Reactions and Electrical Properties of Ti/n-GaN Contacts

1997 ◽  
Vol 2 ◽  
Author(s):  
Holger Cordes ◽  
Y. A. Chang
Keyword(s):  
Electrical Properties ◽  
Diffusion Path ◽  
Interfacial Reactions ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Transmission Line Method ◽  
Current Voltage ◽  
Specific Contact ◽  
Current Voltage Characteristics ◽  
Ar Gas

The phase equilibria in the ternary Ti-Ga-N have been investigated. Interfacial reactions in Ti/GaN contacts have been studied by diffusion couple experiments. The ternary phase Ti2GaN was confirmed by x-ray diffraction in bulk samples as well as in massive Ti/GaN diffusion couples and annealed Ti thin films on GaN. The diffusion path in samples, annealed at 850°C in Ar gas, is GaN/TiN/Ti2GaN/Ti3Ga/Ti. A planar TiN layer forms in direct contact to GaN and governs the electrical properties of annealed Ti/GaN contacts. Thin film contacts were fabricated by sputtering Ti on MOVPE grown n-GaN (5×1017cm−3) and subsequent rapid thermal annealing in an Argon atmosphere. Initially non-linear current-voltage characteristics become ohmic after annealing and a specific contact resistance of approximately 10−2 Ωcm2, measured with the circular transmission line method, was found after annealing at 9000C for 1 min.

Optimization of Ni/Nb Ratio for High-Temperature-Reliable Ni/Nb Silicide Ohmic Contact on 4H-SiC

2019 ◽  
Vol 963 ◽  
pp. 498-501
Author(s):  
Vuong Van Cuong ◽  
Seiji Ishikawa ◽  
Hiroshi Sezaki ◽  
Tomonori Maeda ◽  
Satoshi Yasuno ◽  
...  
Keyword(s):  
High Temperature ◽  
Ohmic Contact ◽  
Contact Resistivity ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Transfer Length ◽  
Ohmic Behavior ◽  
Specific Contact ◽  
Specific Contact Resistivity

Low specific contact resistivity and high-temperature reliability of the Ni (x)/Nb (100-x) (where x = 25, 50, 75 nm) ohmic contact to 4H-SiC were investigated. After the annealing process at 1000°C for 3 min in N2 ambient, the I-V curves indicated that all the contacts exhibited the ohmic behaviors. Based on the transfer length method, the specific contact resistivity of the contacts were extracted. High concentration of Ni was responsible for low specific contact resistance of the Ni (75)/Nb (25)/4H-SiC sample by the formation of Ni2Si compound after the fabrication process. However, this contact lost the ohmic behavior at low temperature of 150°C. Whereas, both Ni (50)/Nb (50)/4H-SiC and Ni (25)/Nb (75)/4H-SiC contacts remained the ohmic behavior for 100-hour aging at 400°C. Two-dimensional X-ray diffraction analyses showed that the presence of carbon agglomeration formed at the interface of the Ni (75)/Nb (25)/4H-SiC contact caused the degradation of this sample when being aged at high temperature environment. Meanwhile, higher concentration of Nb in the Ni (50)/Nb (50)/4H-SiC and Ni (25)/Nb (75)/4H-SiC samples improved the ability to collect the excess carbon atoms and thus enhanced the high temperature reliability of these contacts when operating in high temperature ambient. Considering both low specific contact resistivity and high temperature reliability, the Ni (50)/Nb (50)/4H-SiC contact can be a good candidate for harsh environment applications.

Fabrication and Characterization of Ohmic Contacts to 3C-SiC Layers Grown on Silicon

2019 ◽  
Vol 963 ◽  
pp. 485-489
Author(s):  
Monia Spera ◽  
Giuseppe Greco ◽  
Raffaella Lo Nigro ◽  
Salvatore di Franco ◽  
Domenico Corso ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Specific Contact ◽  
Fabrication And Characterization ◽  
P Type

This paper reports on the formation and characterization of Ohmic contacts to n-type and p-type type 3C-SiC layers grown on silicon substrates. In particular, Ohmic contact behavior was obtained either using Ni or Ti/Al/Ni layers annealed at 950°C. The values of the specific contact resistance ρc estimated by means of circular TLM (C-TLM) structures varied in the range ~ 10-3-10-5 Ωcm2, depending on the doping level of the 3C-SiC layer. A structural analysis performed by X-Ray Diffraction (XRD) allowed to identify the main phases formed upon annealing, i.e., Ni2Si and Al3Ni2. The morphology of the reacted contacts depended on that of the underlying substrate. The results can be useful for the development of a variety of devices on the cubic 3C-SiC polytype.

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.

The Reliability of Multilevel Metallization on InGaAs/GaAs Layers

1994 ◽  
Vol 337 ◽  
Author(s):  
Edward Y. Chang ◽  
J.S. Chen ◽  
J.W. Wu ◽  
K.C. Lin
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Molecular Beam ◽  
Specific Contact Resistance ◽  
Transmission Line Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Specific Contact ◽  
Secondary Ion ◽  
Contact Metal

ABSTRACTNon-alloyed ohmic contacts using Ti/Pt/Au and Ni/Ge/Au on InGaAs/GaAs layers grown by Molecular Beam Epitaxy (MBE) have been investigated. The n-type InGaAs film has a doping concentration higher than 1X1019 cm-3. Specific contact resistance below 2X10-7 Ωcm2 could be easily achieved with Ti/Pt/Au. Due to the layer intermixing and outdiffusion of In and Ga, the specific contact resistance and sheet resistance increase after thermal treatment. When Ni/Ge/Au is used as the contact metal, the outdiffusion of In and Ga atoms is more severe than that of Ti/Pt/Au. After annealing at 450°C for two minutes, the Au4In formed and the characteristics of the contact became worse. All the phenomena illustrated above have been observed and investigated by Transmission Line Model, X-ray diffraction, Auger Electron Spectroscopy and Secondary Ion Mass Spectrum. As far as the thermal stability is concerned, it is convinced that Ti/Pt/Au is the best one of these two non-alloyed ohmic contact studied.

Ohmic Contact in P-HEMT Wafer Using Metallization with Ge/Au/Ni/Au

2014 ◽  
Vol 896 ◽  
pp. 351-353
Author(s):  
Asban Dolah ◽  
Muhammad Azmi Abd Hamid ◽  
Mohamad Deraman ◽  
Ashaari Yusof ◽  
Nor Azhadi Ngah ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Specific Contact Resistance ◽  
Semiconductor Interface ◽  
Transmission Line Method ◽  
Metal Thickness ◽  
Specific Contact ◽  
Lift Off ◽  
Electrical Characterizations ◽  
Metal Layers

In this study, Ohmic contact were fabricated on AlGaAs HEMTs structure. A good metal-semiconductor interface are essentially for achieving lower specific contact resistance. An AlGaAs epi wafer was supply by the vendor. AlGaAs substrate was cleaned using wet chemical etching. Electrodes were fabricated through a sequenced of lithography, cleaning, sputtering and lift-off processes. The electrodes were made with metal layers of Ge, Au and Ni. Parameters such as metal thickness, annealing temperatures (from 300°C to 400°C) and annealing time were varies during fabrication process. Electrical characterizations after annealing are carried out using transmission line method (TLM) to obtain the specific contact resistance. Annealing temperature between 340°C to 360°C produced contact resistance below 5 x 10ˉ³Ω/cm-2.

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