Submicron Pseudomorphic Hemt’S Using Non-Alloyed Ohmic Contacts with Contrast Enhancement.

1990 ◽  
Vol 181 ◽  
Author(s):  
Ph. Jansen ◽  
W. De Raedt ◽  
M. Van Hove ◽  
R. Jonckheere ◽  
R. Pereira ◽  
...  
Keyword(s):  
Electron Beam ◽  
Contact Resistance ◽  
Electron Beam Lithography ◽  
High Performance ◽  
Ohmic Contacts ◽  
Sintering Temperature ◽  
Enhancement Mode ◽  
First Time ◽  
Lower Contact ◽  
Very High

ABSTRACTWe report for the first time the realization of submicron pseudomorphic Al.15, Ga.85As-In.20Ga.80As HEMT’s with non-alloyed Pd/Ge ohmic coi tacts. Best results of contact resistance were obtained at a sintering temperature of 340°C with values as low as 0.057 Ωmm. Enhanced contrast, needed for accurate alignment of the gate by electron-beam lithography, was obtained by using Pd/Ge/Ti/Pd and Pd/Ge/Ti/Pt metal sequences. These contacts exhibited even lower contact resistances than the standard Pd/Ge contacts. Although Pd/Ge/Ti/Pd exhibits good morphology, reaction is witnessed at the edges, reducing the accuracy of alignment.Processed enhancement mode devices exhibit maximum transconductances in excess of 520 mS/mm and currents of 300 mA/mm for 0.3 micron gatelength. This study shows that the contact resistance is no longer a restriction for obtaining very high transconductances in high performance devices.

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.

Laser annealed ohmic contact to n+-GaAs

1983 ◽  
Vol 61 (8) ◽  
pp. 1218-1221 ◽  
Author(s):  
P. Sircar
Keyword(s):  
Surface Morphology ◽  
Contact Resistance ◽  
Excimer Laser ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Laser Annealing ◽  
Furnace Annealing ◽  
Gaas Substrates ◽  
Thin Nickel ◽  
Lower Contact

Ohmic contacts were made on n+-GaAs substrates by evaporating a gold–germanium eutectic film with or without a thin nickel overlayer and then alloying these samples either in a furnace or by means of an excimer laser. It is found that laser annealing gives a better surface morphology and a lower contact resistance than furnace annealing.

Transport Measurements of Individual Bi Nanowires

1999 ◽  
Vol 582 ◽  
Author(s):  
Stephen B. Cronin ◽  
Yu Ming Lin ◽  
Takaaki Koga ◽  
Jackie Y. Ying ◽  
Mildred S. Dresselhaus
Keyword(s):  
Electron Beam ◽  
Temperature Dependence ◽  
Electron Beam Lithography ◽  
Ohmic Contacts ◽  
Physical Significance ◽  
Alumina Template ◽  
Burn Out ◽  
Bi Nanowire ◽  
Lithography Technique ◽  
Confined System

ABSTRACTTransport properties are reported for Bi nanowires, prepared by the filling of an alumina template with molten Bi. The temperature dependence of the resistance is presented for such arrays of Bi nanowires with diameters in the 40 to 200nm range. The data are understood qualitatively on the basis of a model for a quantum-confined system. Finally, a 4-point measurement is performed on an individual Bi nanowire prepared by using an electron beam lithography technique. Techniques for handling the practical issues of non-ohmic contacts and wire burn-out are given. The physical significance of the final results of the measurements are discussed in light of various scattering mechanisms in the nanowire.

scholarly journals Writing Nano-Scale Patterns on Insulators Using Variable Pressure Electron-Beam Lithography

2005 ◽  
Vol 13 (6) ◽  
pp. 42-43
Author(s):  
Floyd Miller ◽  
David Frey
Keyword(s):  
Electron Beam ◽  
Electron Beam Lithography ◽  
Incident Beam ◽  
Variable Pressure ◽  
Positioning Accuracy ◽  
Incident Electron Beam ◽  
Research Environments ◽  
Reasonable Cost ◽  
Electron Microscopes ◽  
Very High

Electron-beam lithography offers very high resolution patterns without the need for masks. Systems based on electron microscopes offer entry into electron-beam lithography at reasonable cost. Such systems are becoming popular in research environments due to their versatility and reasonable cost.While these systems work well they do have problems writing on insulating substrates. The insulating substrate causes charge to build up from the incident electron-beam. As the charge builds up on the surface of the insulator, the incident beam is distorted and moved in x and y. The result is a lack of positioning accuracy on the patterns as well as pattern distortion.

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