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Improved oxide passivation of AlGaN/GaN high electron mobility transistors
 

Summary: Improved oxide passivation of AlGaN/GaN high electron mobility
transistors
B. P. Gila, M. Hlad, A. H. Onstine, R. Frazier, G. T. Thaler, A. Herrero, E. Lambers,
C. R. Abernathy, and S. J. Peartona
University of Florida, Materials Science and Engineering, Gainesville, Florida 32611
T. Anderson, S. Jang, and F. Ren
University of Florida, Chemical Engineering, Gainesville, Florida 32611
N. Moser, R. C. Fitch, and M. Freund
Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433
Received 12 April 2005; accepted 9 September 2005; published online 12 October 2005
MgO has proven effective in the past as a surface passivation layer to minimize current collapse in
AlGaN/GaN high electron mobility transistors HEMTs . However, MgO is not environmentally
stable and more stable oxides need to be developed. MgCaO can be produced that is lattice matched
to the GaN. Three samples were grown with 0%, 50% and 75% of Ca, which had respective lattice
mismatches of -6.5% for MgO, -1% for Mg0.50Ca0.50O and +4% for Mg0.25Ca0.75O. Drain
saturation current in HENTs had increases of 4.5% and 1%, respectively, for Mg0.5Ca0.5O and
Mg0.25Ca0.75O passivated devices. However, there was a 10% decrease for the device passivated
with pure MgO. This was due to strain applied on the nitride HEMT by the oxide, which is
consistent with the piezoelectric effect in the nitride HEMT by the oxide, which is consistent with
the piezoelectric effect in the nitride form the lattice mismatch between AlGaN and GaN. From

  

Source: Anderson, Timothy J. - Chemical Engineering Department, University of Florida

 

Collections: Materials Science