Morphological and electrical comparison of Ti and Ta based ohmic contacts for AlGaN/GaN-on-SiC HFETs
Journal article, 2017
The morphology and impact on leakage currents of two different ohmic metal stacks for GaN based transistor devices is investigated in this work. The results have implications for the performance and reliability of a GaN transistor device. A low temperature Ta based and a higher temperature anneal Ti based metallization are compared. The low temperature process shows a smoother metal semiconductor interface together with several orders of magnitude lower vertical and lateral leakage compared to the conventional higher temperature process. In addition to the leakage tests, back bias ramping experiments are performed unveiling potential advantages of the conventional approach in mitigating current collapse. However the low leakage will enable higher voltage operation making the low temperature process the preferable choice for high power RF applications, if simultaneously current collapse can be controlled.
Ohmic contact
Morphology
Current collapse
Leakage current
GaN
Transistor
Author
A. Pooth
IQE (Europe) Ltd.
University of Bristol
Johan Bergsten
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
Niklas Rorsman
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
H. Hirshy
Cardiff University
R. Perks
Cardiff University
Paul J. Tasker
Cardiff University
T. Martin
IQE (Europe) Ltd.
R. F. Webster
University of Bristol
D. Cherns
University of Bristol
M. J. Uren
University of Bristol
M. Kuball
University of Bristol
Microelectronics and Reliability
0026-2714 (ISSN)
Vol. 68 2-4Subject Categories
Electrical Engineering, Electronic Engineering, Information Engineering
DOI
10.1016/j.microrel.2016.11.002