ABSTRACT: The effects of Si Cl <sub>4</sub> reactive-ion-etching (RIE) plasma treatment on n- Ga N and n- Al <sub>0.20</sub> Ga <sub>0.80</sub> N surfaces, and the subsequent cleaning of the surfaces using ammonium hydroxide ( N H <sub>4</sub> O H ) , hydrochloric acid (HCl), and buffered oxide etch (BOE) solutions, have been investigated using x-ray photoelectron spectroscopy and Auger electron spectroscopy measurements. Of these cleaning schemes, BOE was found to be the most effective treatment to remove oxides from the surfaces of the Si Cl <sub>4</sub> plasma treated samples. The Si Cl <sub>4</sub> plasma treatment of GaN and AlGaN resulted in the blueshift of Ga–N ( Ga 3d) peaks to higher binding energies corresponding to a shift of the Fermi level (E<sub> F </sub>) toward the conduction band edge at the surface. It has been reported that this type of shift is caused by the creation of N vacancies, which act as n -type dopant [D. W. Jenkins and J. D. Dow, Phys. Rev. B. 39, 3317 (1989); M. E. Lin, Z. F. Fan, Z. Ma, L. H. Allen, and H. Morkoç, Appl. Phys. Lett. 64, 887 (1994); A. T. Ping, Q. Chen, J. W. Yang, M. A. Khan, and I. Adesida, J. Electron. Mater. 27, 261 (1998)] on the surface due to Si Cl <sub>4</sub> plasma treatment. This corresponds to an increase in n -type dopant density on the surface. Thus, Si Cl <sub>4</sub> plasma treatment in a RIE system thins the Schottky barrier heights of n- Ga N and <-
formula>n- Al Ga N and aids in the formation of ohmic contacts on such surfaces.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 12/2005; · 1.34 Impact Factor