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Proceedings Paper

Investigation of cross-sectional potential distribution in GaN-based field effect transistors by Kelvin probe force microscopy
Author(s): M. Kaneko; A. Hinoki; A. Suzuki; T. Araki; Y. Nanishi
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Paper Abstract

Cross-sectional potential distribution of AlGaN/GaN HFETs with and without surface passivation by silicon nitride (SiNx) has been investigated by using Kelvin probe force microscopy to study the effect of the surface passivation layer on an electric field under high operating bias conditions. The measured FETs exhibited DC characteristics of the maximum drain current of 750 mA/mm, threshold voltage of -5 V, and the transconductance of 150 mS/mm. For the bias condition of the gate voltage of -5 V and the drain voltage of 40 V, the electric field is mainly concentrated at three areas without relation to the presence or absence of the surface passivation layer. One is the mid-point between the gate and drain electrodes at FET surface. The others are the mid-depth of GaN buffer layer under the drain electrode and the interface between GaN buffer and SiC substrates from drain edge toward source electrode. Near the surface of SiNx-passivated AlGaN/GaN HFETs, it is confirmed that the intensity of electric field concentration decreases compared to that of no-passivated AlGaN/GaN HFETs. It is considered that this result originates in the decrease of the surface charge by SiNx passivation. In addition, It is found that the electric field concentration near the GaN/SiC interface has a tendency to become stronger rather than that between the drain and gate electrodes by SiNx passivation.

Paper Details

Date Published: 15 February 2008
PDF: 9 pages
Proc. SPIE 6894, Gallium Nitride Materials and Devices III, 689418 (15 February 2008); doi: 10.1117/12.765947
Show Author Affiliations
M. Kaneko, Ritsumeikan Univ. (Japan)
A. Hinoki, Ritsumeikan Univ. (Japan)
A. Suzuki, Ritsumeikan Univ. (Japan)
T. Araki, Ritsumeikan Univ. (Japan)
Y. Nanishi, Ritsumeikan Univ. (Japan)

Published in SPIE Proceedings Vol. 6894:
Gallium Nitride Materials and Devices III
Hadis Morkoç; Cole W. Litton; Jen-Inn Chyi; Yasushi Nanishi; Euijoon Yoon, Editor(s)

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