TY - JOUR
T1 - Effective Schottky Barrier Height Model for N-Polar and Ga-Polar GaN by Polarization-Induced Surface Charges with Finite Thickness
AU - Suemitsu, Tetsuya
AU - Makabe, Isao
N1 - Funding Information:
This article is based on the results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). On the Tohoku University side, part of this work was also supported by the Japan Society of the Promotion of Science under KAKENHI grant no. 19H02165.
Publisher Copyright:
© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/4/1
Y1 - 2020/4/1
N2 - The nitrogen-polar GaN material system is a promising candidate for high-frequency applications, such as those in the millimeter-wave range. Schottky barrier height is one of fundamental parameters necessary for device applications of N-polar GaN. Herein, vertical Schottky diodes for both N-polar and Ga-polar GaN are prepared, and it is found through experiments that the barrier height of N-polar GaN is smaller than that of Ga-polar GaN by 0.21 V. This difference in the barrier height stems from the polarization-induced surface charge layer of a few angstroms thickness under the surface. Numerical calculation of band profiles suggests that a significant band bending caused by the large amount of polarization charges pushes the conduction band energy downward (upward) in the N-polar (Ga-polar) surface depending on the sign of the polarization charges, which results in two different effective Schottky barrier heights. This difference is explained by assuming the polarization-charge layer thickness of about 5 Å. A simple analytical model to estimate the difference in barrier heights between the two polarities is also proposed.
AB - The nitrogen-polar GaN material system is a promising candidate for high-frequency applications, such as those in the millimeter-wave range. Schottky barrier height is one of fundamental parameters necessary for device applications of N-polar GaN. Herein, vertical Schottky diodes for both N-polar and Ga-polar GaN are prepared, and it is found through experiments that the barrier height of N-polar GaN is smaller than that of Ga-polar GaN by 0.21 V. This difference in the barrier height stems from the polarization-induced surface charge layer of a few angstroms thickness under the surface. Numerical calculation of band profiles suggests that a significant band bending caused by the large amount of polarization charges pushes the conduction band energy downward (upward) in the N-polar (Ga-polar) surface depending on the sign of the polarization charges, which results in two different effective Schottky barrier heights. This difference is explained by assuming the polarization-charge layer thickness of about 5 Å. A simple analytical model to estimate the difference in barrier heights between the two polarities is also proposed.
KW - barrier height
KW - gallium nitride
KW - nitrogen-polar materials
KW - polarization charges
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U2 - 10.1002/pssb.201900528
DO - 10.1002/pssb.201900528
M3 - Article
AN - SCOPUS:85077856008
VL - 257
JO - Physica Status Solidi (B): Basic Research
JF - Physica Status Solidi (B): Basic Research
SN - 0370-1972
IS - 4
M1 - 1900528
ER -