Optimizing n+ Ohmic Contacts on GaAs for HemtS

1992 ◽  
Vol 260 ◽  
Author(s):  
H. M. Harris ◽  
J. R. Farley
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
High Performance ◽  
Ohmic Contacts ◽  
Layer Structure ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
Alloy Process ◽  
Spacer Layer ◽  
Better Than

ABSTRACTLow ohmic contact resistance is essential for high performance microwave and millimeter wave transistors. Rapid thermal processing (RTP) has been used to optimize the ohmic contact resistance of gold - germanium / nickel / gold metallizations on gallium arsenide (GaAs) layers for high electron mobility transistor (HEMT) applications. A HEMT layer structure consisting of a 9000Å buffer layer grown on a semi-insulating substrate followed by a 20Å undoped AlGaAs spacer layer, a 700Å Al0.22Ga0.78 As layer doped at 1.0 × 1018cm-3and a 500Å GaAs cap layer doped at 1.5 × 1018 cm°C to 450°C. Time at temperature was varied from 10 seconds to 1 minute. Optimum conditions for our equipment and layer structure were found to be 365°C for 30 seconds. These conditions produced contact resistances of 0.08 ohm-mm (approximately 2.0 times better than the standard furnace alloy process).

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.

Refinement of low-resistance Ni–Ge–Au ohmic contacts to n+ GaAs using screening and response surface experiments

1996 ◽  
Vol 11 (5) ◽  
pp. 1238-1243 ◽  
Author(s):  
Nancy E. Lumpkin ◽  
Warren King ◽  
T. L. Tansley
Keyword(s):  
Contact Resistance ◽  
Response Surface ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
High Electron Mobility Transistors ◽  
Process Variable ◽  
Fractional Factorial ◽  
Order Effects ◽  
High Electron ◽  
Screening Experiment

Multivariable screening and response surface experiments have been performed to model ohmic contact resistance (Rc) of a Ni–Ge–Au ohmic metal process for n+ GaAs-based high electron mobility transistors (HEMTs). Seven variables were examined via a fractional factorial screening experiment to rank the effects of each process variable. The results of the screening experiment indicated that the most significant variables were total Ge and Au evaporated thickness, Ge-to-Au ratio, and the post-alloy cooling time. Response surface experiments were designed around these three variables to examine the first- and second-order effects. The results enabled the development of an empirical model of ohmic contact resistance from which a new low value of 0.03 ± 0.03 Ω · mm (one-sigma) was predicted. Twenty confirmation runs on the new process indicated an average Rc of 0.06 ± 0.02 Ω · mm (one-sigma), with a range of 0.02 Ω · mm to 0.11 Ω · mm, a reduction from the previous average process value of 0.14 ± 0.07 Ω · mm (one-sigma).

Electrical Comparison of Ta/Ti/Al/Mo/Au and Ti/Al/Mo/Au Ohmic Contacts on Undoped GaN HEMTs Structure with AlN Interlayer

2007 ◽  
Vol 17 (01) ◽  
pp. 85-89 ◽  
Author(s):  
Yunju Sun ◽  
Lester F. Eastman
Keyword(s):  
Contact Resistance ◽  
Electron Mobility ◽  
Ohmic Contacts ◽  
High Electron Mobility Transistor ◽  
Metal Contact ◽  
High Electron ◽  
Transfer Resistance ◽  
High Electron Mobility ◽  
Hemt Structure ◽  
Gan Hemts

A significant improvement of contact transfer resistance on undoped GaN/AlGaN/AlN (10 Å)/ GaN high electron mobility transistor (HEMT) structure was demonstrated using a Ta/Ti/Al/Mo/Au metallization scheme compared to a Ti/Al/Mo/Au metallization scheme. A contact resistance as low as 0.16 ± 0.03 ohm - mm was achieved by rapid thermal annealing of evaporated Ta (125 Å)/ Ti (150 Å)/ Al (900 Å)/ Mo (400 Å)/ Au (500 Å) metal contact at 700 °C for 1 min followed by 800 °C for 30 sec in a N 2 ambient. An excellent edge acuity was also demonstrated for the annealed Ta/Ti/Al/Mo/Au ohmic contacts.

scholarly journals AlGaN/GaN High Electron Mobility Transistors on Semi-Insulating Ammono-GaN Substrates with Regrown Ohmic Contacts

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 546 ◽  
Author(s):  
Wojciech Wojtasiak ◽  
Marcin Góralczyk ◽  
Daniel Gryglewski ◽  
Marcin Zając ◽  
Robert Kucharski ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Ohmic Contacts ◽  
High Electron Mobility Transistors ◽  
High Electron Mobility Transistor ◽  
Maximum Output ◽  
High Electron ◽  
Output Current ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Access Resistance

AlGaN/GaN high electron mobility transistors on semi-insulating bulk ammonothermal GaN have been investigated. By application of regrown ohmic contacts, the problem with obtaining low resistance ohmic contacts to low-dislocation high electron mobility transistor (HEMT) structures was solved. The maximum output current was about 1 A/mm and contact resistances was in the range of 0.3–0.6 Ω ·mm. Good microwave performance was obtained due to the absence of parasitic elements such as high access resistance.

scholarly journals Bandwidth Improvement of MMIC Single-Pole-Double-Throw Passive HEMT Switches with Radial Stubs in Impedance-Transformation Networks

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 270
Author(s):  
Yi-Fan Tsao ◽  
Joachim Würfl ◽  
Heng-Tung Hsu
Keyword(s):  
Insertion Loss ◽  
Electron Mobility ◽  
High Electron Mobility Transistor ◽  
Conventional Approach ◽  
High Electron ◽  
Frequency Range ◽  
Fractional Bandwidth ◽  
High Electron Mobility ◽  
State Capacitance ◽  
Better Than

In this paper, we propose a new configuration for improving the isolation bandwidth of MMIC single-pole-double-throw (SPDT) passive high-electron-mobility transistor (HEMT) switches operating at millimeter frequency range. While the conventional configuration adopted open-stub loading for compensation of the off-state capacitance, radial stubs were introduced in our approach to improve the operational bandwidth of the SPDT switch. Implemented in 0.15 m GaAs pHEMT technology, the proposed configuration exhibited a measured insertion loss of less than 2.5 dB with better than 30 dB isolation level over the frequency range from 33 GHz to 44 GHz. In terms of the bandwidth of operation, the proposed configuration achieved a fractional bandwidth of 28.5% compared to that of 12.3% for the conventional approach. Such superior bandwidth performance is mainly attributed to the less frequency dependent nature of the radial stubs.

scholarly journals Layered boron nitride enabling high-performance AlGaN/GaN high electron mobility transistor

2020 ◽  
Vol 829 ◽  
pp. 154542 ◽  
Author(s):  
Bing Ren ◽  
Meiyong Liao ◽  
Masatomo Sumiya ◽  
Jian Li ◽  
Lei Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Mobility ◽  
High Performance ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
High Electron Mobility
Sign in / Sign up

Export Citation Format

Share Document