Schottky Diodes on MOCVD Grown AlGaN Films.
A. Y. Polyakov, N.B. Smirnov, A.V. Govorkov
Institute of Rare Metals
D. W. Greve
Department of Electrical and Computer Engineering, Carnegie Mellon University
M. Skowronski, M. Shin
Department of Materials Science and Engineering, Carnegie Mellon University
Joan M. Redwing
Epitronics/ATMI
This article was received on Monday, June 22, 1998 and
accepted on Friday, October 16, 1998. Abstract
Au Schottky diodes were prepared by vacuum evaporation or by plasma
sputtering on n-AlGaN(Si) films with Al mole fractions of 0, 0.11 or 0.23. The
barrier heights were deduced from C-V and I-T measurements. The difference
between the C-V and I-T results was less than 0.1 eV for the barriers deposited at
300 °C on HF etched samles with prior in situ heating at 450
°C. For low deposition temperatures (about 150°C) C-V and
I-T methods give results differing by some tenths of an eV. For deposition
temperatures exceeding 450°C the diodes were very leaky. The barrier
heights were 0.8 eV, 0. 9 eV and 1.1 eV for AlGaN with compositions of 0,
0.11 and 0.23. For plasma sputtered diodes on GaN and AlGaN (x=0.11) samples,
the difference in C-V and I-T results was quite considerable and admittance
spectroscopy indicated the presence of deep electron traps at 0.12-0.14 eV
that were absent in vacuum evaporated diodes. For similar diodes on AlGaN(x=0.23) samples
the results of C-V and I-T measurements were very close and no traps at
0.12-0.14 eV could be detected. This difference is most likely due to damage
caused by low energy ions. More Al-rich films are less susceptible to such
damage. Persistent photocapacitance was observed in n-AlGaN Schottky diodes
after illumination at 85K. Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 3, 37(1998).
last updated Friday, October 16, 1998 12:49:36 PM.© 1998 The Materials Research Society
