| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2-ThM |
| Session: | Low Damage Processing |
| Presenter: | M. Sekine, Nagoya University, Japan |
| Authors: | R. Kometani, Nagoya University, Japan S. Chen, Nagoya University, Japan J. Park, Nagoya University, Japan J. Cao, Nagoya University, Japan Y. Lu, Nagoya University, Japan K. Ishikawa, Nagoya University, Japan K. Takeda, Nagoya University, Japan H. Kondo, Nagoya University, Japan H. Amano, Nagoya University, Japan M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Experimental - Samples were Si-doped GaN epitaxial layer with thickness of 1 μm grown by metal organic chemical vapor deposition (MOCVD) on sapphire substrates. After removed native oxides off chemically, the samples of GaN were partially etched off by using capacitively coupled plasma (CCP) reactor. Pure argon gas of 50 sccm was introduced and a pressure of 10 Pa was maintained. Plasmas were sustained by applying radio frequency (13.56 MHz or 100 MHz) power to a sample stage which temperature was maintained at 600°C. After the plasma processes for 10 min., morphology of the sample was measured by the atomic force microscopy (AFM), chemical composition was evaluated by the x-ray photoelectron spectroscopy (XPS).
AFM images of initial sample was shown smooth surface and also surface morphology was not significantly changed Just after annealed at 600°C for 10 min. However, after exposed Ar plasma at elevated temperature of 600°C for 10min, surface roughness was observed in particular. This is considered that the observed roughness caused by forming metallic-Ga precipitates on the surface, which was supported by results increase of metallic Ga bonding by XPS analysis. Namely, this indicates that favorable volatilization of nitrogen created Ga-droplets and promoted to roughen the surface at 600°C.
On contrary, surface morphology after N2 plasma was relatively smooth although the high temperature. The results in smoothness were possibly resulted by difference in Ga droplet formation because of suppression of metallic Ga formation by reacting of reactive N species.
In this study, we report a method to control surface properties on plasma etched GaN through experiments carried out with samples at elevated temperatures. Further detailed discussion will be conducted.
Acknowledgement - This work was partly supported by the Knowledge Cluster Initiative (Second Stage)-Tokai Region Nanotechnology Manufacturing Cluster.1) R. Kawakami et al., Thin Solid Film. 516, 3478 (2008).
2) R. Kometani et al., Jpn. Soc. Appl. Phys. Spring Meeting (2012), 30a-M-11.