Nanolayered Au/Ti/Al Ohmic Contacts to P-Type SiC: Electrical, Morphological and Chemical Properties Depending on the Contact Composition

2007 ◽  
Vol 556-557 ◽  
pp. 725-728 ◽  
Author(s):  
Lilyana Kolaklieva ◽  
Roumen Kakanakov ◽  
Iva Avramova ◽  
Ts. Marinova
Keyword(s):  
Surface Roughness ◽  
Surface Morphology ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Chemical Properties ◽  
Interface Chemistry ◽  
Optimal Annealing Temperature ◽  
P Type ◽  
Contact Resistivities ◽  
And Chemical Properties

Electrical, morphological and chemical properties of nanolayered Au/Ti/Al ohmic contacts with different Ti:Al ratio are investigated. Contact resistivities of 1.42×10-5 ⋅cm2 and 1.21×10-5 ⋅cm2 are achieved for Au/Ti(70)/Al(30) and Au/Ti(30)/Al(70) contacts, respectively. It is found that the Ti:Al ratio does not affect the lowest resistivity value but influences on the optimal annealing temperature at which it is obtained. The different optimal annealing temperature provokes different element distributions and interface chemistry of the annealed contacts. An increase of the Al concentration in the contact composition causes essentially the surface morphology leading to an increase in surface roughness of the as-deposited and annealed contacts.

Composition and Interface Chemistry Dependence in Ohmic Contacts to GaN HEMT Structures on the Ti/Al Ratio and Annealing Conditions

2009 ◽  
Vol 615-617 ◽  
pp. 951-954 ◽  
Author(s):  
Lilyana Kolaklieva ◽  
Roumen Kakanakov ◽  
Plamen Stefanov ◽  
Volker Cimalla ◽  
S. Maroldt ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Chemical Properties ◽  
Contact Layer ◽  
Element Distribution ◽  
Interface Chemistry ◽  
Gan Hemt ◽  
Annealing Conditions ◽  
Optimal Annealing Temperature ◽  
And Chemical Properties

Electrical, thermal and chemical properties of Ti/Al/Ti/Au ohmic contacts with different former Ti-Al ratio are investigated for application in GaN HEMTs. Lowest resistivity of 4.22x10-5 Ω.cm2 has been obtained to the channel of the HEMT structure. It is found out that the initial Ti/Al ratio influences the optimal annealing temperature at which the lowest resistivity is obtained and the element distribution and interface chemistry of the annealed contacts. XPS analysis revealed two compounds contributing to ohmic properties: an intermetal compound AlAu2 in the contact layer and a semimetal TiN at the interface with GaN.

Structural Analysis of Au/Ti/Al/SiC Contacts in Dependence on the Initial Composition and Annealing

2010 ◽  
Vol 12 ◽  
pp. 55-63 ◽  
Author(s):  
Lilyana Kolaklieva ◽  
Roumen Kakanakov ◽  
Maya Marinova ◽  
Efstathios K. Polychroniadis
Keyword(s):  
Carrier Transport ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Strong Dependence ◽  
Initial Contact ◽  
Initial Composition ◽  
Tem Analysis ◽  
Optimal Annealing Temperature ◽  
Two Phases ◽  
P Type

The dependence of the structure and composition of nanolayered Au/Ti/Al ohmic contacts to p-type 4H-SiC on the initial Ti:Al ratio has been investigated. Two contact compositions, Au/Ti(70%)/Al(30%) and Au/Ti(30%)/Al(70%), have been studied regarding the electrical properties, structure, composition and annealing temperature in the interval 850 – 1000o C. The correlation between the electrical behaviour and structure of the annealed contacts is discussed. Very low resistivity of 1.42x10-5 .cm2 after annealing at 900o C has been obtained for the contact having an initial composition Ti:Al (30:70), while the lowest resistivity of 1.21x10-5 .cm2 has been measured for the contact with a composition Ti:Al (70:30) after annealing at 1000o C. Strong dependence of the contact structure on the Ti:Al ratio and annealing temperature, respectively, has been found out. A presence of two phases, Au2Ti and Al3Ti, in all contacts has been determined after annealing, despite the temperature value and Ti:Al ratio. The TEM analysis reveals that titanium and aluminum silicides and carbides are formed after annealing as the Ti:Al ratio affects the kind of silicides and carbides created. It is obtained that the initial composition of the deposited metal layers influences only the phase composition of the annealed contact but not the grain sizes of the dominant phases formed. The origin of the ohmic properties improvement is explained by the formation of Ti3SiC2 compound and/or enhanced carrier transport by the presence of metal spikes into SiC depending on the initial contact composition and as consequence the optimal annealing temperature.

Study of the electrical, thermal and chemical properties of Pd ohmic contacts to p-type 4H-SiC: dependence on annealing conditions

1999 ◽  
Vol 61-62 ◽  
pp. 291-295 ◽  
Author(s):  
L Kassamakova ◽  
R Kakanakov ◽  
N Nordell ◽  
S Savage ◽  
A Kakanakova-Georgieva ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Chemical Properties ◽  
Annealing Conditions ◽  
P Type ◽  
And Chemical Properties

Improvement of the Specific Contact Resistance on P-Type 4H-SiC by Using a Highly P-Typed Doped 4H-SiC Layer Selectively Grown by VLS Transport

2014 ◽  
Vol 806 ◽  
pp. 57-60
Author(s):  
Nicolas Thierry-Jebali ◽  
Arthur Vo-Ha ◽  
Davy Carole ◽  
Mihai Lazar ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Schottky Barrier Height ◽  
Annealing Temperature ◽  
Process Condition ◽  
Specific Contact Resistance ◽  
High Doping Level ◽  
Annealing Temperatures ◽  
Specific Contact ◽  
P Type

This work reports on the improvement of ohmic contacts made on heavily p-type doped 4H-SiC epitaxial layer selectively grown by Vapor-Liquid-Solid (VLS) transport. Even before any annealing process, the contact is ohmic. This behavior can be explained by the high doping level of the VLS layer (Al concentration > 1020 cm-3) as characterized by SIMS profiling. Upon variation of annealing temperatures, a minimum value of the Specific Contact Resistance (SCR) down to 1.3x10-6 Ω.cm2 has been obtained for both 500 °C and 800 °C annealing temperature. However, a large variation of the SCR was observed for a same process condition. This variation is mainly attributed to a variation of the Schottky Barrier Height.

scholarly journals Comparison of Electrical Properties of Ohmic Contact Realized on p-Type 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 639-642
Author(s):  
Duy Minh Nguyen ◽  
Christophe Raynaud ◽  
Mihai Lazar ◽  
Heu Vang ◽  
Dominique Planson
Keyword(s):  
Surface Roughness ◽  
Electrical Properties ◽  
Contact Resistance ◽  
Carrier Mobility ◽  
Ohmic Contacts ◽  
Series Resistance ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type ◽  
Post Implantation

N+ 4H-SiC commercial substrates with n-type epilayers have been used to realize bipolar diodes and TLM structures. The p-type emitter of diodes was realized by Al implantations followed by a post-implantation annealing with or without a graphite capping layer. Ohmic contacts were formed by depositing Ti/Ni on the backside and Ni/Al on the topside of the wafer. It appears that capping the sample during the annealing reduces considerably the surface roughness and the specific contact resistance. Sheet resistance and specific contact resistance as low as 2kΩ/□ and respectively 1.75×10-4 Ωcm² at 300 K have been obtained. I-V measurements as a function of temperature have been performed from ~100 to ~500 K. The variations of the series resistance vs. temperature can be explained by the freeze-out of carriers and by the variation of carrier mobility.

Comparative Study of Electrical and Microstructural Properties of 4H-SiC MOSFETs

2012 ◽  
Vol 717-720 ◽  
pp. 437-440 ◽  
Author(s):  
Christian Strenger ◽  
Volker Haeublein ◽  
Tobias Erlbacher ◽  
Anton J. Bauer ◽  
Heiner Ryssel ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Interfacial Layer ◽  
Chemical Properties ◽  
Microstructural Properties ◽  
Layer Formation ◽  
Carbon Distribution ◽  
Transmission Electron ◽  
Inversion Channel ◽  
P Type ◽  
And Chemical Properties

N-channel MOSFETs were manufactured on p-type and on p-implanted, n-type 4H-SiC substrates. The electron mobility in the inversion channel was measured to be correlated with the structural and chemical properties determined by transmission electron microscopy. With regard to what was previously discussed in the literature, interfacial layer formation and carbon distribution across the SiC/SiO2 interface were considered in relation with the measured Hall electron mobility.

Investigation of Ni/Al/Ti Ohmic Contact on N-Type 4H-SiC

2021 ◽  
Vol 1045 ◽  
pp. 186-193
Author(s):  
Meng Qian Xue ◽  
Cai Ping Wan ◽  
Nian Nian Ge ◽  
Heng Yu Xu
Keyword(s):  
Surface Morphology ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Alloy System ◽  
Ohmic Resistance ◽  
Annealing Conditions ◽  
Atomic Force ◽  
Metal Composition ◽  
Specific Contact ◽  
P Type

In order to understand the contribution of various metals in the formation of ohmic contacts, Ni/Al/Ti ohmic contacts on n-type 4H-SiC in terms of a different annealing temperature and Ti composition are investigated, which is more difficult to form than p-type ohmic contact. The formation of the Ni/Al/Ti metal alloy system is much more sensitive to metal composition than annealing conditions. With the increase of metal composition, the contact with a high Ti content yields a lower specific contact resistivity compared with the low Ti contact. The annealed surface morphology and phase resultants were examined by scanning electron microscopy (SEM) and atomic force microscope (AFM), respectively. With the increase of Ti components, the surface morphology of the samples becomes more uniform and smoother, while the surface roughness remains unchanged. It implies that Ti metal can not only reduce the ohmic resistance, but also protect the surface of the sample and maintain the roughness.

Ultraprecision Lapping for the Zirconia Ceramic Plane

2013 ◽  
Vol 797 ◽  
pp. 129-134 ◽  
Author(s):  
Hong Bo Ji ◽  
Yan Peng ◽  
Fen Fen Zhou ◽  
Wei Gang Guo ◽  
Bing Hai Lv ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Smooth Surface ◽  
Chemical Properties ◽  
Zirconia Ceramic ◽  
Physical And Chemical Properties ◽  
Material Removal Mechanism ◽  
Physical And Chemical ◽  
Surface Construction ◽  
And Chemical Properties

Zirconia ceramic widely applied in the fields of electronics, instrumentations and mechanical manufacture for its good physical and chemical properties. The ultraprecision lapping technology for the Zirconia ceramic is studied in this paper, and the influence of the different lapping parameters such as slurry, load and lapping velocity on the surface roughness of Zirconia ceramic is discussed. The evolution of surface construction is observed with the microscope to analysis the material removal mechanism. An extremely smooth surface with roughness 6.55nm Ra is obtained in the ultraprecision process. It is also found that the gap in the material will limit improvement of surface roughness and a better surface roughness of 4.72nm Ra was observed when using more compactly material lapped by same method.

Nano-Analytical and Electrical Characterization of 4H-SiC MOSFETs

2012 ◽  
Vol 711 ◽  
pp. 134-138 ◽  
Author(s):  
Ana Maria Beltran ◽  
Sylvie Schamm-Chardon ◽  
Vincent Mortet ◽  
Mathieu Lefebvre ◽  
Elena Bedel-Pereira ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Electronic Devices ◽  
Chemical Properties ◽  
Electrical Characterization ◽  
Power Electronic ◽  
Layer Formation ◽  
Transmission Electron ◽  
P Type ◽  
And Chemical Properties

4H-SiC presents great advantages for its use in power electronic devices working at particular conditions. However the development of MOSFETs based on this material is limited by mobility degradation. N-channel SiC MOSFETs were manufactured on p-type epitaxial and p-implanted substrates and the electron mobility in the inversion channels was measured to be correlated with their structural and chemical properties determined by transmission electron microscopy methods. With regard to what was previously discussed in the literature, transition layer formation and carbon distribution across the SiC-SiO2interface are considered in relation with the measured low electron mobility of the MOSFETS.

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