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Study of the flat band voltage shift of metal/insulator/n‐GaN capacitors by annealing
Author(s) -
Kikawa Junjiroh,
Kaneko Masamitsu,
Otake Hirotaka,
Fujishima Tatsuya,
Chikamatsu Kentaro,
Yamaguchi Atsushi,
Nanishi Yasushi
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200983671
Subject(s) - annealing (glass) , dipole , insulator (electricity) , condensed matter physics , capacitor , materials science , voltage , optoelectronics , physics , quantum mechanics , composite material
The flat‐band voltage ( V FB ) of metal/insulator (SiN or SiO 2 )/n‐GaN capacitors has been investigated focusing on the effect of postdeposition annealing (PDA). We have found that V FB shifts toward the negative‐bias direction with increasing annealing temperature. The estimated activation energies of a trap related to the shift in V FB are approximately 160 meV for SiN and 130 meV for SiO 2 . The difference between these energies is small. The dependence of V FB on SiN thickness indicates that fixed charges causing the shift in V FB exist at the SiN/GaN interface. This implies that the reactions at both the SiN/GaN and SiO 2 /GaN interfaces are promoted by the same mechanism. We propose an interface dipole model to explain the shift in V FB . During the deposition of the insulator, each dipole is oriented in a random direction, because the process reaction is carried out at room temperature. It is considered that PDA might cause the randomly oriented dipoles to face in the same direction, resulting in the total moment of the dipoles becoming larger than that before annealing. We also performed Kelvin force microscopy (KFM) measurement to observe the charged state of SiN directly.