Ultralow-Contact-Resistance Au-Free Ohmic Contacts With Low Annealing Temperature on AlGaN/GaN Heterostructures

2018 ◽  
Vol 39 (6) ◽  
pp. 847-850 ◽  
Author(s):  
Jinhan Zhang ◽  
Xuanwu Kang ◽  
Xinhua Wang ◽  
Sen Huang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Annealing Temperature

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 Ohmic contacts to Si-implanted and un-implanted n-type GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
J. Brown ◽  
J Ramer ◽  
K. ZHeng ◽  
L.F. Lester ◽  
S.D. Hersee ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Contact Resistivity ◽  
Contact Structures ◽  
Specific Contact Resistance ◽  
Resistance Variation ◽  
Specific Contact ◽  
Metal Layers ◽  
Nitrogen Vacancies

ABSTRACTWe report on ohmic contacts to Si-implanted and un-implanted n-type GaN on sapphire. A ring shaped contact design avoids the need to isolate the contact structures by additional implantation or etching. Metal layers of Al and Ti/Al were investigated. On un-implanted GaN, post metalization annealing was performed in an RTA for 30 seconds in N2 at temperatures of 700, 800, and 900°C, A minimum specific contact resistance (rc) of 1.4×10−5 Ω-cm2 was measured for Ti/Al at an annealing temperature of 800°C. Although these values are reasonably low, variations of 95% in specific contact resistance were measured within a 500 µm distance on the wafer. These results are most likely caused by the presence of compensating hydrogen. Specific contact resistance variation was reduced from 95% to 10% by annealing at 900°C prior to metalization. On Si-implanted GaN, un-annealed ohmic contacts were formed with Ti/Al metalization. The implant activation anneal of 1120°C generates nitrogen vacancies that leave the surface heavily n-type, which makes un-annealed ohmic contacts with low contact resistivity possible.

W2B based High Thermal Stability Ohmic Contacts to n-GaN

2005 ◽  
Vol 892 ◽  
Author(s):  
Rohit Khanna ◽  
S J Pearton ◽  
C J Kao ◽  
I I Kravchenko ◽  
F Ren ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Operating Temperature ◽  
Dominant Role ◽  
Electronic Devices ◽  
High Thermal Stability ◽  
Power Electronic ◽  
Current Transport ◽  
Excellent Stability

AbstractA novel metallization scheme for Ohmic contact (Ti/Al/ W2B /Ti/Au) to n-GaN using high temperature boride was studied using contact resistance, scanning electron microscopy and Auger Electron Spectroscopy measurements. A minimum contact resistance of 7×10-6 Ω.cm2 was achieved for W2B based scheme at an annealing temperature of 800 °C. Contact resistances were found to be essentially independent of measurement temperature, indicating that tunneling plays a dominant role in the current transport. The outdiffusion of Ti to the surface at temperatures of ∼500°C, and at 800°C the onset of intermixing of Al within the contact was found to occur. By 1000°C, the contact showed a reacted appearance and AES showed almost complete intermixing of the metallization. The reliability measurements for the contact resistance of W2B based contact showed excellent stability for extended periods at 200°C, which simulates the type of device operating temperature that might be expected for operation of GaN-based power electronic devices.

Interfacial Reactions between In/Pd and GaAs

1991 ◽  
Vol 230 ◽  
Author(s):  
Z. Ma ◽  
L. H. Allen ◽  
B. Blanpain ◽  
Q. Z. Hong ◽  
J. W. Mayer ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Interfacial Microstructure ◽  
Limiting Factor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ohmic Behavior ◽  
Sims Analysis ◽  
Secondary Ion

AbstractInterfacial microstructure of In/Pd ohmic contacts to n-GaAs was studied by various X-ray diffraction techniques and secondary ion mass spectroscopy (SIMS). Analysis of this interface after various annealing showed that In1-xGaxAs compounds are formed at the interface and the composition of these compounds depends upon the annealing temperature. As the temperature increases, the stoichiometry of the Inrich compounds tends toward higher concentrations of Ga. The low contact resistance is achieved by dividing the Schottky barrier between metal and GaAs into two barriers due to metal/Inl-xGaxAs and In1-xGaxAs/GaAs. The barrier due to In1-xGaxAs/GaAs is believed to be the main limiting factor in lowering of contact resistance. The observed ohmic behavior for sample annealed at 500°C for 20 s is attributed to the further reduction of this barrier.

Process Parameters Influence on Specific Contact Resistance (SCR) Value for TiAl Ohmic Contacts on GaN Grown on Sapphire

2009 ◽  
Vol 615-617 ◽  
pp. 955-958 ◽  
Author(s):  
Olivier Ménard ◽  
Frédéric Cayrel ◽  
Emmanuel Collard ◽  
Daniel Alquier
Keyword(s):  
Contact Resistance ◽  
Process Parameters ◽  
Ohmic Contacts ◽  
Annealing Temperature ◽  
Contact Process ◽  
Surface Cleaning ◽  
Specific Contact Resistance ◽  
Process Conditions ◽  
Specific Contact ◽  
Aln Buffer

In this work, Ti/Al bilayer sputtered ohmic contacts on n-type Gallium Nitride films were studied as a function of process parameters such as Ti thickness, surface cleaning procedure or annealing temperature. Epilayers, with doping concentration of 5.8x1018 at.cm-3, were grown on sapphire using AlN buffer layer. Electrical characterizations were made using circular Transfer Length Method (cTLM) patterns with a four probes equipment. Specific Contact Resistance (SCR) was then extracted for all the process conditions. Our results show that surface treatment is not a critical step in the ohmic contact process while annealing temperature has a larger impact. Finally, SCR values of 1x10-5 Ω.cm2 can be reproducibly achieved, which is of high interest for future devices fabrication using this material.

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

1987 ◽  
Vol 45 ◽  
pp. 326-327
Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Microstructural Characterization ◽  
Almost Everywhere ◽  
Spacer Layer ◽  
Good Contact ◽  
The Relationship ◽  
Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

Ohmic Contacts to GaAs

1982 ◽  
Vol 18 ◽  
Author(s):  
Norman Braslau
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Spatially Inhomogeneous ◽  
Heavily Doped

The present capability of obtaining ohmic contacts to GaAs over a range of doping levels is reviewed. Possible models of transport across the metalsemiconductor interface are discussed and contact techniques are described. The widely used Au—Ge alloyed contact is seen to have a spatially inhomogeneous interface which appears to control its contact resistance. The most satisfactory process at this time is to alloy into a previously fabricated heavily doped layer.

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