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Proceedings Paper

Effects of polarization fields on avalanche breakdown of AlGaN quantum-well photodiode
Author(s): Sheng-Kun Zhang; Wubao Wang; Robert R. Alfano; Amir M. Dabiran; Andrew M. Wowchak; Peter P. Chow
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Paper Abstract

Polarization-induced electric fields in AlGaN quantum wells have important effects on avalanche breakdown of AlGaN quantum-well photodiodes. When the polarization-induced fields within the AlGaN well layers have the same direction as applied electric field, they can help enhance impact ionization rate and decrease threshold voltage of avalanche breakdown of AlGaN avalanche photodiodes. However, according to previous research on avalanche breakdown of AlGaN photodiodes, no distinct breakdown threshold was observed from current-voltage curve. Instead, a soft avalanche breakdown was observed across applied voltage ranging from zero to a few volts while electroluminescence spectra show a threshold of about 10 V for avalanche breakdown. In this work, by considering impact ionization of defect levels and carrier screening effect, impact ionization coefficients are calculated as functions of applied voltage and the soft breakdown is well explained. It is also found that strong carrier screening effect will decrease impact ionization rate in a certain range of voltage thus affecting device performance.

Paper Details

Date Published: 27 February 2012
PDF: 6 pages
Proc. SPIE 8262, Gallium Nitride Materials and Devices VII, 826227 (27 February 2012); doi: 10.1117/12.910189
Show Author Affiliations
Sheng-Kun Zhang, Borough of Manhattan Community College., CUNY (United States)
Wubao Wang, The City College of New York, CUNY (United States)
Robert R. Alfano, The City College of New York, CUnY (United States)
Amir M. Dabiran, SVT Associates, Inc. (United States)
Andrew M. Wowchak, SVT Associates, Inc. (United States)
Peter P. Chow, SVT Associates, Inc. (United States)

Published in SPIE Proceedings Vol. 8262:
Gallium Nitride Materials and Devices VII
Jen-Inn Chyi; Yasushi Nanishi; Hadis Morkoç; Joachim Piprek; Euijoon Yoon, Editor(s)

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