Paper PS-ThM11
Room Temperature Radical Annealing of Plasma Damaged Gallium Nitride
Thursday, November 3, 2011, 11:20 am, Room 201
| Session: |
Neutral Beam and Low Damage Processing |
| Presenter: |
Shang Chen, Nagoya University, Japan |
| Authors: |
S. Chen, Nagoya University, Japan
Y. Lu, Nagoya University, Japan
K. Takeda, Nagoya University, Japan
K. Ishikawa, Nagoya University, Japan
H. Kondo, Nagoya University, Japan
H. Kano, NU Eco-engineering Co., Ltd, Japan
H. Amano, Nagoya University, Japan
Y. Tokuda, Aichi Insititute of Technology, Japan
T. Egawa, Nagoya Institute of Technology, Japan
M. Sekine, Nagoya University, Japan
M. Hori, Nagoya University, Japan
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| Correspondent: |
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This paper reports an attempt of low-temperature recovery for gallium nitride (GaN) damaged by the exposure of a chlorine-based etching plasma. The work is motivated by the challenge for manufacturing highly-reliable GaN based devices which have a great deal of potential in optical, high-frequency, and high-power electronics field. So far, high temperature annealing or nitrogen plasma were used as the post-process. However, the high-temperature treatment could not restore the reduced atomic ratio of nitrogen on the damaged surface. The nitrogen plasma introduces damage by the ion bombardment. In this study, a high-density radical anneling in room temperature was newly proposed and evaluated in all in-situ experimental system consisted of etching, radical annealing, and surface analysis.
Radicals and ions extracted from a chlorine plasma were irradiated to n-GaN with an ion dose of 5 x 1016cm-2 at 500 eV [1]. Then the radical annealing using nitrogen radical (N*) or hydrogen radical (H*) with a radical dose of 1 x 1018cm-2was applied using a high-density radical source [2] at room temperature. The X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) evaluation carried out after each process.
In N* annealing case, the surface chloride was removed and N/Ga was improved, but there was no change in the composition ratio of oxygen (O). On the other hand, hydrogen radical (H*) could efficiently remove O, and N/Ga was improved greatly. Other characteristic findings were that Ga-Ga (metallic Ga) was observed in the Ga 3d spectra and the surface roughness increased from 0.335 to 0.646 nm rms.
As a result, the radical annealing at room temperature was shown to be very effective for improving GaN stoichiometry to achieve a better interface, whereas the condition should be optimized very carefully.
Acknowledgments
This work was supported by the knowledge Cluster Initiative (the Second Stage), the MEXT, Japan.
[1] S. Chen, et al., Proc. 63rd GEC/7th ICRP (Paris, 2010), BT1-005.
[2] S. Chen, et al., Jpn. J. Appl. Phys. 50, 01AE03 (2011).