W, WSix and Ti/Al Low Resistance Ohmic Contacts to InGaN, InN and InAlN

1996 ◽  
Vol 421 ◽  
Author(s):  
C.B. Vartuli ◽  
S.J. Pearton ◽  
C.R. Abernathy ◽  
J.D. MacKenzie ◽  
R.J. Shul ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Subsequent Annealing ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Specific Contact

AbstractW, WSi0.44 and Ti/Al contacts were examined on n+ In0.65Ga0.35N, InN and In0.75Al0.25N. W was found to produce low specific contact resistance (Qc ˜ 10−7 Ω cm2) ohmic contacts to InGaN, with significant reaction between metal and semiconductor at 900 °C mainly due to out diffusion of In and N. WSix showed an as-deposited Qc of 4×10−7 Ω cm2 but this degraded significantly with subsequent annealing. Ti/Al contacts were stable to Ω 600 °C (Qc, ˜ 4×10−7 Ω cm2 at ≤600 °C). The surfaces of these contacts remain smooth to 800 °C for W and WSix and 650 °C for Ti/Al. InN contacted with W and Ti/Al produced ohmic contacts with Qc ˜ 10−7 Ω cm2 and for WSix Qc ˜ Ω cm2.All remained smooth to ˜ 600 °C, but exhibited significant interdiffusion of In, N, W and Ti respectively at higher temperatures. The contact resistances for all three metallization schemes were ≥ 10−4 Ω.cm2 on InAIN, and degrades with subsequent annealing. The Ti/Al was found to react with the InA1N above 400 °C, causing the contact resistance to increase rapidly. W and WSix proved to be more stable with Qc ˜ 10−2 and 10−3 Ω cm2 up to 650 °C and 700 °C respectively.

Low-Resistance Electrical Contacts to p-Type GaN by Using InxGa1-xN Cap Layers

2001 ◽  
Vol 693 ◽  
Author(s):  
Th. Gessmann ◽  
Y.-L. Li ◽  
J. W. Graff ◽  
E. F. Schubert ◽  
J. K. Sheu
Keyword(s):  
Contact Resistance ◽  
Electric Fields ◽  
Ohmic Contacts ◽  
Electrical Contacts ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Transmission Line Method ◽  
Specific Contact ◽  
P Type ◽  
20 Nm

AbstractA novel type of low-resistance ohmic contacts is demonstrated utilizing polarization-induced electric fields in thin p-type InGaN layers on p-type GaN. An increase of the hole tunneling probability through the barrier and a concomitant significant decrease of the specific contact resistance can be attributed to a reduction of the tunneling barrier width in the InGaN capping layers due to the polarization-induced electric fields. The specific contact resistance of Ni (10 nm) / Au (30 nm) contacts deposited on the InGaN capping layers was determined by the transmission line method. Specific contact resistances of 1.2 × 10-2 Ω cm2 and 6 × 10-3 & cm2 were obtained for capping layer thicknesses of 20 nm and 2 nm, respectively.

Low Resistance Ti-Si-C Ohmic Contacts for 4H-SiC Power Devices Using Laser Annealing

2017 ◽  
Vol 897 ◽  
pp. 399-402 ◽  
Author(s):  
Milantha de Silva ◽  
Teruhisa Kawasaki ◽  
Takamaro Kikkawa ◽  
Shinichiro Kuroki
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Laser Annealing ◽  
Electrical Contact ◽  
Nickel Silicide ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Specific Contact ◽  
Face Side ◽  
Non Equilibrium

Non-equilibrium laser silicidations for low-resistance ohmic contact to 4H-SiC C-face with Titanium was demonstrated. Ti is one of carbon-interstitial type metals. In a conventional nickel silicide (NiSi) electrode on SiC, a carbon agglomeration at the silicide/SiC interface occurs, and contact resistance becomes larger. For suppressing the carbon agglomeration, in this research, nanoseconds non-equilibrium laser annealing was introduced, and also Ti was introduced to form both silicide and carbide. Ti (75, 100 nm)/SiC and Ni (75, 100 nm)/SiC contacts were formed on C-face side of 4H-SiC substrates. Electrical contact properties were investigated after 40 nanoseconds pulse laser annealing in Ar ambient and rapid thermal annealing. As the result, In the case of laser annealing, the lowest specific contact resistance of 2.4×10-4 Ωcm2 was obtained in Ti (75 nm)/SiC sample in the laser power of 2.5 J/cm2.

Low Resistance Non-Transparent ohmic Pt-contacts on p-GaN

2001 ◽  
Vol 693 ◽  
Author(s):  
Andreas Weimar ◽  
Stefan Bader ◽  
Georg Brüderl ◽  
Volker Kümmler
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Hole Concentration ◽  
Blue Laser ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Specific Contact ◽  
Device Operation ◽  
Secondary Ion ◽  
Resistance Value

AbstractThe metal – p-GaN junction for low resistance ohmic contacts is still a challenge to be applied in GaN-based opto electronics as well as in power and high frequency devices. Currently, we try to improve the performance of our blue laser diodes. In order to decrease heat generation during device operation it is necessary to ensure as small contact resistances as possible.In this work, we achieved a specific contact resistance value of RC = 1.8 ± 1.7. 10-5 Ωcm2 for Pt-contacts on MOVPE-grown p-GaN. The Pt-layers were deposited by e-beam and thermally assisted vacuum evaporation after a standard cleaning process. For evaluation of Rc we used optimised circular TLM test patterns defined by photolithography. Best contacts were formed by annealing in Nitrogen athmosphere at 500°C.We also investigated the dependence of the contact resistance on the Mg doping concentration. Therefore p-GaN layers with different Mg-concentrations were grown on SiC-substrates and Pt-contacts were processed. For those samples, we investigated the Mg-concentrations, verified by secondary ion mass spectroscopy (SIMS), the hole concentrations and mobilities in dependence of C(Mg), which we obtained from HALL-measurements, and the contact and sheet resistances, measured by circular TLM measurements.The experiments showed that the optimum Mg-concentration for low contact resistances is higher than 2 1019 cm-3 which was found to provide a maximum hole concentration near 7 1017 cm-3. The influence of self-compensation in p-GaN in bulk and near interfaces will be discussed.

Pt/Ti Low Resistance Non-Alloyed Ohmic Contacts to InP-Based Photonic Devices

1989 ◽  
Vol 146 ◽  
Author(s):  
A. Katz ◽  
S. N. G. Chu ◽  
P. M. Thomas ◽  
W. C. Dautremont-Smith
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Metal Layer ◽  
Photonic Devices ◽  
Electrical Performance ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Specific Contact ◽  
20 Nm ◽  
Resistance Value

ABSTRACTPt/ri low resistance non-alloyed ohmic contacts to p-InP-based contact layers in photonic devices, which were formed by rapid thermal processing (RTP), were studied. E-gun evaporated Pt/Ti metallization deposited onto 1.5· 1019 cm−3 Zn doped In0.53Ga0.47 As yielded the best electrical performance. These contacts were ohmic as deposited with a specific contact resistance value of 3.0 · 10−4 Ωcm2. RTP at higher temperatures led to decrease of the specific contact resistance to 3.4 · 10−8 Ωcm2 (0.08Ωmm) as a result of heating at 450°C for 30 sec. This heat treatment caused only a limited interfacial reaction (about 20 nm thick) between the Ti and the InGaAs, resulted in a thermally stable contact and induced tensile stress of 5.6 · 109 dyne · cm−2 at the metal layer but without degrading the adhesion. Heating at temperatures higher than 500°C resulted in an extensive interaction and degradation of the contact.

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.

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.

Ni-Al-Ti Ohmic Contacts with Preserved Form Factor and Few 10- 4 Ωcm2 Specific Resistance on 0.1-1 Ωcm p-Type 4H-SiC

2018 ◽  
Vol 924 ◽  
pp. 385-388 ◽  
Author(s):  
Roberta Nipoti ◽  
Maurizio Puzzanghera ◽  
Maria Concetta Canino ◽  
Giovanna Sozzi ◽  
Paolo Fedeli
Keyword(s):  
Form Factor ◽  
Contact Resistance ◽  
Contact Area ◽  
Room Temperature ◽  
Ohmic Contacts ◽  
Specific Resistance ◽  
Thickness Ratio ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type

This study shows that a thin Ni film on Al/Ti/4H-SiC metal pads allows to preserve the pad form factor during a 1000 °C/2 min treatment, provided that the Al and Ti film thicknesses are sufficiently thin. Moreover, by reducing the Al to Ti thickness ratio, droplet formation in the contact area is avoided and a mirror-like appearance is obtained. This optimal contact morphology corresponds to a specific contact resistance of few 10-4Ωcm2at room temperature on p-type 4H-SiC with resistivity in the range 0.1 – 1 Ωcm.

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