The Effects of Ion Beam Mixing on Rapid Thermal Annealed Ohmic Contacts to N-GaAs

1990 ◽  
Vol 181 ◽  
Author(s):  
Seemi Kazmi ◽  
Roman V. Kruzelecky ◽  
David A. Thompson
Keyword(s):  
Surface Morphology ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Specific Contact Resistance ◽  
Ion Beam Mixing ◽  
Specific Contact

ABSTRACTNi/Ge/Au and Ni/Ge/Pd contacts have been made on 1018 cm-3 n-type GaAs. The contacts were subjected to ion beam mixing through the metallization using 70-130 keV Se+ ions and subsequently subjected to rapid thermal annealing (RTA). These are compared with unimplanted contacts produced by RTA techniques on the same substrate. The specific contact resistance ,pc, has been measured for the two systems. In addition, the contacts have been studied using Auger depth profiling and SEM studies have been used to determine surface morphology. Values of pc ∽ 10-6 -10-7 ohm-cm2 have been measured. It is observed that ion beam mixing or the addition of a Ti overlayer (to the Ni/Ge/Au) improves the contact morphology.

PtIn2 ohmic contacts to n-GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
D. B. Ingerly ◽  
Y. A. Chang ◽  
N. R. Perkins ◽  
T. F. Kuech
Keyword(s):  
Phase Diagram ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Ohmic Contacts ◽  
Depth Profiling ◽  
Reciprocal System ◽  
Specific Contact Resistance ◽  
Contact Interface ◽  
Ohmic Behavior

ABSTRACTA new metallization scheme has been developed to form ohmic contacts to n-GaN. Contacts were fabricated by sputtering the intermetallic compound, PtIn2 on n-GaN (n ∼ 5 ×l017 cm−3) grown by metalorganic vapor phase epitaxy (MOVPE) with some of the contacts subjected to rapid thermal annealing. Contacts in the as-deposited state exhibited nearly ohmic behavior with a specific contact resistance of 1.2 × 10−2 Ω cm2. Contacts subjected to rapid thermal annealing at 800 °C for 1 minute exhibited linear current-voltage characteristics and a decrease in contact resistance. To rationalize the reaction at the contact interface the phase diagram of the PtIn2-PtGa2-InN-GaN reciprocal system at 800 °C was calculated based on known and estimated thermodynamic values. This phase diagram suggests that there will be a solid state exchange of In and Ga atoms at the Ptln2/GaN contact interface producing (InxGa1-x)N and Pt(In,Ga)2. Results from Auger depth profiling used to examine the Ptln2/n-GaN contacts are consistent with this estimated phase diagram information. It is proposed that the formation of (InxGa1-x)N at the contact interface is responsible for the ohmic behavior of Ptln2 contacts.

scholarly journals A Study on the Chemistry of Epitaxial Ti3SiC2 Formation on 4H-SiC Using Al-Ti Annealing

2015 ◽  
Vol 821-823 ◽  
pp. 432-435 ◽  
Author(s):  
Tony Abi-Tannous ◽  
Maher Soueidan ◽  
Gabriel Ferro ◽  
Mihai Lazar ◽  
Berangère Toury ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Specific Contact Resistance ◽  
Free Sample ◽  
Elemental Analyses ◽  
Specific Contact ◽  
P Type ◽  
Al Oxide

In order to form Ti3SiC2 on 4H-SiC(0001) 8°-off, 200 nm of Ti30Al70 was deposited onto SiC substrates by magnetron sputtering from pure Ti30Al70 targets. The samples were then annealed at 1000°C for 10 min under Ar atmosphere in a Rapid Thermal Annealing (RTA) furnace. Structural analyses reveal the formation of epitaxial hexagonal Ti3SiC2 (0001) oriented. Elemental analyses show that high amount of Al and O elements are present inside the deposit. Obviously, the formation of Ti3SiC2 is accompanied by parasitic Al oxide, probably due to some unwanted oxygen residual in the RTA chamber. By using proper backing steps before the annealing, the deposit is not anymore composed of only Ti3SiC2 but accompanied with other compounds (Al3Ti, and Al). On the oxide-free sample, the specific contact resistance ρc of the Ti3SiC2 based contact on p-type 4H-SiC (having Na= 2×1019 cm-3) was measured to be as low as 6×10-5 Ω.cm2.

Ion Beam Treatment of Ohmic Contacts to n-TYPE Hg1-xCdxTe

1992 ◽  
Vol 260 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves ◽  
Yuan H. Li
Keyword(s):  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Ion Beam ◽  
Specific Contact Resistance ◽  
Range Analysis ◽  
Ion Beam Mixing ◽  
Auger Depth Profile ◽  
Specific Contact ◽  
Implantation Techniques ◽  
Ion Beam Treatment

ABSTRACTThe application of ion beam mixing and ion implantation techniques in the formation of ohmic contacts to n-Hg1-xCdxTe (x = 0.6, 0.7) has been investigated. For experiments in ion beam mixing, an indium layer (15nm thick) on Hg1-xCdxTe wasbombarded with 45keV Te+ ions at doses ranging from 1 × 1013 to 1 × 1016 cm2. Minimum values of specific contact resistance, pc, of 4 × 10-4Ωcm-2 were measured for a dose of 1 × 1016 cm-2 after 200°C annealing; pc was independent of dose in this range. Analysis of the interfaces by Auger depth profile and Rutherford backscattering spectrometry has shown that ion beam mixing produced an enhanced indiffusion of indium. In comparison, samples which were ion implanted with In+ at 50keV prior to metalisation showed a reduction in pc which was strongly dependent on dosage.

SNOM Investigation of Surface Morphology Changes during Cr/Au Contact Fabrication on Single-Crystal CVD Diamond

2006 ◽  
Vol 527-529 ◽  
pp. 1587-1590 ◽  
Author(s):  
D. Doneddu ◽  
Owen J. Guy ◽  
R.M. Baylis ◽  
L. Chen ◽  
P.R. Dunstan ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Contact Resistance ◽  
Single Crystal ◽  
Ohmic Contacts ◽  
Cvd Diamond ◽  
Diamond Surface ◽  
Specific Contact Resistance ◽  
Metal Contacts ◽  
High Quality ◽  
Specific Contact

The formation of metal/diamond Ohmic contacts is essential to most electronic devices. In order to form a good Ohmic contact to diamond a carbide-forming metal such as Ti or Cr is necessary. In this study, Cr/Au contacts to heavily boron-doped single crystal CVD diamond were fabricated by subsequent deposition of Cr and Au. The surface morphology and specific contact resistance of diamond/Cr/Au contacts has been investigated. The reaction between the Cr metal and the diamond during annealing gives an improved specific contact resistance. However, this reaction also causes a significant change in the surface morphology. The surface morphology of singlecrystal diamond is shown to greatly influence the properties of metal contacts to diamond. Shearforce mode atomic force microscopy (AFM) investigations have been used to examine the diamond surface before metallization, and after removing the metal contact. The initial diamond surface was predominantly smooth, apart from some scratches from the polishing process. Surface RMS roughness values of around 0.4nm were found. Correlation between surface morphology and contact resistance has been found, with rougher surfaces exhibiting a barrier to conduction. An understanding of the contact formation process is an essential step in achieving high quality Ohmic contacts which are vital in the fabrication of high quality diamond devices.

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.

Current Transport in Ti/Al/Ni/Au Ohmic Contacts to GaN and AlGaN

2007 ◽  
Vol 556-557 ◽  
pp. 1027-1030 ◽  
Author(s):  
Ferdinando Iucolano ◽  
Fabrizio Roccaforte ◽  
Filippo Giannazzo ◽  
A. Alberti ◽  
Vito Raineri
Keyword(s):  
Contact Resistance ◽  
Field Emission ◽  
Ohmic Contacts ◽  
Theoretical Models ◽  
Specific Contact Resistance ◽  
Strong Increase ◽  
Current Transport ◽  
Electrical Characteristics ◽  
Structural And Electrical Properties ◽  
Specific Contact

In this work, the structural and electrical properties of Ti/Al/Ni/Au contacts on n-type Gallium Nitride were studied. An ohmic behaviour was observed after annealing above 700°C. The structural analysis showed the formation of an interfacial TiN layer and different phases in the reacted layer (AlNi, AlAu4, Al2Au) upon annealing. The temperature dependence of the specific contact resistance demonstrated that the current transport occurs through thermoionic field emission in the contacts annealed at 600°C, and field emission after annealing at higher temperatures. By fitting the data with theoretical models, a reduction of the Schottky barrier from 1.21eV after annealing at 600°C to 0.81eV at 800°C was demonstrated, together with a strong increase of the carrier concentration at the interface. The reduction of the contact resistance upon annealing was discussed by correlating the structural and electrical characteristics of the contacts.

Investigation of Ge, As, and Au Diffusion in Non-Alloyed Epitaxial Au-Ge Ohmic Contacts to n-GaAs Using Secondary Ion Mass Spectroscopy Backside Sputter Depth-Profiling

1991 ◽  
Vol 240 ◽  
Author(s):  
H. S. LEE ◽  
R. T. Lareau ◽  
S. N. Schauer ◽  
R. P. Moerkirk ◽  
K. A. Jones ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
High Concentration ◽  
Ohmic Behavior ◽  
Preferential Sputtering ◽  
Specific Contact ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTA SIMS backside sputter depth-profile technique using marker layers is employed to characterize the diffusion profiles of the Ge, As, and Au in the Au-Ge contacts after annealing at 320 C for various times. This technique overcomes difficulties such as ion beam mixing and preferential sputtering and results in high depth resolution measurements since diffusion profiles are measured from low to high concentration. Localized reactions in the form of islands were observed across the surface of the contact after annealing and were composed of Au, Ge, and As, as determined by SIMS imaging and Auger depth profiling. Backside SIMS profiles indicate both Ge and Au diffusion into the GaAs substrate in the isalnd regions. Ohmic behavior was obtained after a 3 hour anneal with a the lowest average specific contact resistivity found to be ∼ 7 × 100−6 Ω- cm2.

Modelling Geometrical Effects of Parasitic and Contact Resistance of FET Devices

1996 ◽  
Vol 427 ◽  
Author(s):  
Geoffrey K. Reeves ◽  
H. Barry Harrison ◽  
Patrick W. Leech
Keyword(s):  
Contact Resistance ◽  
Material Properties ◽  
Ohmic Contacts ◽  
Difficult Problem ◽  
Specific Contact Resistance ◽  
Metal Silicide ◽  
Transmission Line Model ◽  
Specific Contact ◽  
Geometrical Effects ◽  
Contact Parameters

AbstractThe continual trend in decreasing the dimensions of semiconductor devices results in a number of technological problems. One of the more significant of these is the increase in contact resistance, Rc. In order to understand and counteract this increase, Rc needs to be quantitatively modelled as a function of the geometrical and material properties of the contact. However the use of multiple semiconductor layers for ohmic contacts makes the modelling and calculation of Rc a more difficult problem. In this paper, a Tri-Layer Transmission Line Model (TLTLM) is used to analyse a MOSFET ohmic contact and gatedrain region. A quantitative assessment of the influence on Rc of important contact parameters such as the metal-silicide specific contact resistance, the silicide-silicon specific contact resistance and the gate-drain length can thus be made. The paper further describes some of the problems that may be encountered in defining Rc when the dimensions of certain types of contact found in planar devices decrease.

Ohmic Contacts to p-Type InGaAs/InP with a Graded Bandgap Heterobarrier

1993 ◽  
Vol 318 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Specific Contact Resistance ◽  
Superlattice Structure ◽  
Specific Contact ◽  
P Type ◽  
Metal Layers ◽  
Anneal Temperature ◽  
Graded Bandgap

ABSTRACTOhmic contacts to p-type InP with an In0.47Ga0.53As buffer layer and an interposed superlattice of 50 Å In0.47Ga0.53As/ 50 Å InP have been investigated. Initial studies of contacts to In0.47Ga0.53As/ InP without the superlattice structure have shown that Pd/Zn/Pd/Au metallization produced a lower specific contact resistance (pc = 1.1 × 10−4 Ω cm2) than Pd/Ge/Au, and over a wider range of anneal temperature than Au/Zn/Au. The incorporation of the superlattice in the p-In0.47Ga0.53As/ InP structure resulted in Pd/Zn/Pd/Au contacts with pc of 3.2 × 10−5 Ω cm2 as-deposited and 7.5 × 10−6 Ω.cm2 after a 500 °C anneal. The presence of Pd/Zn in the metallization was shown as important in reducing pc. Significant intermixing of the metal layers and In0.47Ga0.53As occured at ≥ 350 °C, as revealed by Rutherford backscattering spectrometry.

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