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.

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.

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.

Characterization of a Rapid Thermal Annealed TiNxOy/TiSi2 Barrier Layer

1990 ◽  
Vol 181 ◽  
Author(s):  
Sailesh Chittipeddi ◽  
Michael J. Kelly ◽  
Charles M. Dziuba ◽  
Anthony S. Oates ◽  
William T. Cochran
Keyword(s):  
Thin Film ◽  
Annealing Temperature ◽  
Barrier Properties ◽  
Cmos Technology ◽  
Nitrogen Atmosphere ◽  
Titanium Film ◽  
Rapid Thermal Anneal ◽  
Tem Analysis ◽  
P Type

ABSTRACTIn this paper we characterize the thin film formed by rapid thermal anneal of a magnetron sputtered titanium film in a nitrogen atmosphere. The barrier properties of this material have been characterized for both n- and p-type junctions in our CMOS technology. We have characterized the physical properties of the film using Auger, RBS and TEM analysis in the same range of temperatures, and find that as the annealing temperature is increased a better quality TiNxOy film is formed. The electromigration characteristics for Aℓ/TiNxOy/TiSi2 runners, as well as the role that this system plays in minimizing failures due to stress induced voiding are examined in this study.

TEM assessment of GaN/AlGaN/TiAlTiAu and GaN/AlGaN/TiAlPdAu ohmic contacts

2001 ◽  
Vol 693 ◽  
Author(s):  
M W Fay ◽  
G Moldovan ◽  
I Harrison ◽  
J C Birbeck ◽  
B T Hughes ◽  
...  
Keyword(s):  
Interfacial Reaction ◽  
High Temperatures ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Structural Evolution ◽  
Electrical Performance ◽  
Diffusion Front ◽  
Tem Analysis ◽  
Inclusion Formation

AbstractTiAlTiAu and TiAlPdAu contacts to GaN/AlGaN, rapid thermal annealed at temperatures ranging from 650°C to 950°C, have been investigated using conventional and chemical TEM analysis. Ohmic behaviour was seen for TiAlTiAu contacts annealed at 750°C or higher, but was not observed in TiAlPdAu contacts annealed at up to 950°C. The effect of annealing temperature on the structural evolution of the contact is explained in terms of different extents of interfacial reaction. In particular, the formation of TiN after anneals at high temperatures is required to activate the contact. At anneals of 950°C, TiAlTiAu samples show a structure of TiN grains within an interfacial band, with TiN inclusions into the AlGaN preceded by an Al-Au diffusion front. Inclusion formation and the effect on the contact electrical performance is described.

The Effects of Thermal Processing on Interfacial Microstructure for Thin Multilayered Metal Ohmic Contacts to p+-AlGaAs

1995 ◽  
Vol 382 ◽  
Author(s):  
M.W. Cole ◽  
W.Y. Han ◽  
K.A. Jones
Keyword(s):  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Chemical Diffusion ◽  
Interfacial Microstructure ◽  
Specific Contact Resistance ◽  
Interfacial Region ◽  
Electrical Measurements ◽  
Two Phase ◽  
Specific Contact ◽  
P Type

ABSTRACTInterfacial microstructure and phase composition of PtTiGePd ohmic contacts to heavily C doped AlGaAs were investigated as a function of annealing temperature. Results of the material analyses were used to explain the specific contact resistances measured for each thermal treatment. Evidence of interdiffusion and compound formation between AIGaAs and Pd was visible in a Ga rich Pd-Ga-As reaction zone prior to heat treatment. This phase is critical for the formation of Ga vacancies, which upon heating are occupied by in-diffusing Ge. As the annealing temperature was elevated, from 530 - 600°C, As began to out-diffuse. This As out-diffusion, which is critical to the formation of good p-type ohmic contacts, contributed to the creation and development of the two phase TiAs/Pd12Ga2Ge5 interfacial region overlying the AlGaAs substrate. In response to the enhanced As out-diffusion at 600°C, the interfacial region became laterally continuous, compositionally uniform, and the specific contact resistance achieved its minimum value. Athigher annealing temperatures, ∼650°C, the electrical measurements degraded in response to intensive chemical diffusion and development of a broad, non-uniform multi-phased interfacial region.

Effects of Post-Annealing Temperature on the Structure and Electrical Properties of N-Doped ZnO Films

2014 ◽  
Vol 1070-1072 ◽  
pp. 475-478
Author(s):  
Xiang Min Zhao
Keyword(s):  
Electrical Properties ◽  
Annealing Temperature ◽  
Rf Magnetron Sputtering ◽  
Zno Films ◽  
Atomic Force ◽  
Post Annealing ◽  
Optimal Annealing Temperature ◽  
Structure Morphology ◽  
Doped Zno ◽  
P Type

N-doped ZnO films were deposited on Si (100) substrates by radio frequency (RF) magnetron sputtering in N2/Ar2 gas mixture. After the deposition, the films were post-annealed in vacuum at several temperatures from 400°C to 850°C for 60 minutes respectively.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO films following post-annealing. When the annealing temperature is higher than 650°C achieved by the n-type ZnO to the p-type transition and for the better growth of p-type ZnO films, the optimal annealing temperature is 650°C.

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.

Carrier Transport Mechanisms in Ion Implanted and Highly-Doped p-Type 4H-SiC(Al)

2019 ◽  
Vol 963 ◽  
pp. 318-323 ◽  
Author(s):  
Antonella Parisini ◽  
Roberta Nipoti
Keyword(s):  
Doping Level ◽  
Carrier Transport ◽  
Annealing Temperature ◽  
Recent Literature ◽  
Extended Defects ◽  
Transport Mechanisms ◽  
As Doping ◽  
P Type ◽  
Ion Implanted

Fundamental aspects of transport in Al ion implanted p-type 4H-SiC are briefly reviewed, in the light of recent literature. Particular attention is paid on (i) the Hall factor and (ii) the role of disorder in the onset of a variable range hopping mechanism (VRH) at high temperatures as doping level increases, up to a 2D-VRH induced by extended defects in the heaviest doped samples. The study allowed to understand the critical balance between implanted impurity density and annealing temperature that leads to the searched doping level, ensuring an efficient electrical activation of implanted impurities, on a side, and, on the other side, avoiding stacking faults that cause anisotropic hopping transport.

Simultaneous Formation of Ohmic Contacts for Both N- and P-Type 4H-Sic Using Nial-Based Contact Materials

2006 ◽  
Vol 911 ◽  
Author(s):  
Susumu Tsukimoto ◽  
Toshitake Onishi ◽  
Kazuhiro Ito ◽  
Masanori Murakami
Keyword(s):  
Ohmic Contacts ◽  
Field Effect Transistors ◽  
Strong Dependence ◽  
Oxide Semiconductor ◽  
Simultaneous Formation ◽  
Contact Materials ◽  
Specific Contact ◽  
One Step ◽  
Lower Temperature ◽  
P Type

AbstractIn order to simplify a fabrication process of silicon carbide power MOSFETs (metal oxide semiconductor field effect transistors), development of a simultaneous formation process of ohmic contacts to both the p-well and n-source regions of the SiC devices using same contact materials and one step annealing was challenged. We succeeded to develop NiAl-based contact materials which provided ohmic behaviors for both n- and p-type 4H-SiC after one step annealing. The Ni/Al and Ni/Ti/Al ohmic contacts were prepared by depositing sequentially Ni, (Ti) and Al layers with various layer thicknesses onto the n- and p-type SiC substrates which were doped with N at 1 × 1019 cm-3 and with Al at 8 × 1018 cm-3, respectively. The Ni(50 nm)/Al(5 ~ 6 nm) contacts showed ohmic behaviors for both the n- and p-type SiC substrates after annealing at 1000 °C. The Ni(20 nm)/Ti(50 nm)/Al(50 ~ 70 nm) contacts showed ohmic behaviors for both the n- and p-type SiC substrates after annealing at a lower temperature of 800 °C. The specific contact resistances of these contacts were measured to be in the order of 10-3 Ω-cm2 for both p- and n-type SiC, and were found to have strong dependence of the Al layer thicknesses of materials. The interfacial microstructures of the NiAl-based contacts were also observed by transmission electron microscopy (TEM) to understand the current transport mechanism through the metal/SiC interfaces.

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