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.

scholarly journals Омические контакты к эпитаксиальным структурам CVD-алмаза с дельта-слоями бора

2019 ◽  
Vol 53 (10) ◽  
pp. 1386
Author(s):  
Е.А. Архипова ◽  
Е.В. Демидов ◽  
М.Н. Дроздов ◽  
С.А. Краев ◽  
В.И. Шашкин ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Diamond Film ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Current Flow ◽  
Cvd Diamond ◽  
Boron Doped ◽  
Heavily Doped ◽  
Test Cells

Various methods of the formation of ohmic contacts to CVD diamond epitaxial structures with boron doped delta layers (δ-layers) are investigated. In the first approach, an additional thin, heavily doped layer was formed on the surface of the diamond film, to which the ohmic contact was formed. Then, the surface p+-layer between the contact pads was etched out, so the current flow in the structure occurred only through the buried δ-layer. In the second approach, doped diamond was selectively grown in contact windows under the mask of metal after preliminary etching the undoped diamond layer (cap) to the δ-layer. In this case, the heavily doped p+-layer will form a contact to the δ-layer. These approaches are differs by conditions of applicability, the complexity of manufacturing technology, the value of contact resistance. So they can be used to solve tasks in which different quality of contacts is required, such as the formation of transistor structures or test cells for measuring electrophysical characteristics.

Correlation Between the Interfacial Nonuniformity and the Specific Contact Resistance of Ohmic Contacts to Gaas

1990 ◽  
Vol 181 ◽  
Author(s):  
T. Q. Tuy ◽  
I. Mojzes ◽  
V. V. Tuyen ◽  
I. Cseh
Keyword(s):  
Theoretical Model ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Contact Region ◽  
Specific Contact Resistance ◽  
Simultaneous Presence ◽  
Modified Model ◽  
Specific Contact ◽  
Heavily Doped ◽  
Bulk Semiconductor

ABSTRACTConsidering the effect of the simultaneous presence and interaction of the different phases at the contact, a modification of the model presented by Wu and coworkers (Solid-St. Electron. 29 (1986) 489] for explanation of ohmic contact resistance of n-GaAs was developed. The modified model combines the existence of the mixed phase structure of AuGeNi/n-GaAs contact with assumptions proposed by Wu et al. that the specific contact resistance Rc contains two parts Rcl and Rc2, where Rc1 is the specific contact resistance of the alloyed and underlaying doped contact region, and Rc2, is that of the high-low junction between the heavily doped contact region and the bulk semiconductor. The Rc1 depends strongly on the apparent barrier height and the effective impurity concentration formed by doping from the contact alloys during annealing. In the present paper a new theoretical model for Rc1 is proposed and compared with the experimental results.

Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 184 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.50Ω-mim during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 181 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.5Ω-mm during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

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.

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.

Ohmic contacts to pseudomorphic HEMTs with low contact resistance due to enhanced Ge penetration through AlGaAs layers

2008 ◽  
Vol 23 (2) ◽  
pp. 025019 ◽  
Author(s):  
G Sai Saravanan ◽  
K Mahadeva Bhat ◽  
K Muraleedharan ◽  
H P Vyas ◽  
R Muralidharan ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic 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.

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