Characterization of the surface layer of GaAs nitrided by high-density plasma

A high-density N2 plasma was generated after mode jump by a helical antenna surrounded by magnetic coils. In the wavelength region of 600–800 nm, the emission lines from the N2 first positive system and that from N atoms (3p→3s) were also observed, in addition to the emission lines from the N2 second positive and N2+ first negative systems in the ultraviolet and violet regions. At the mode jump, the emission peak intensity from N atoms especially increased. Nitridation of GaAs was performed in the N2 plasma before and after mode jump. N 1s peak intensities from the surface layer nitrided in the N2 plasma after mode jump measured by X-ray photoelectron spectroscopy were 2–5 times larger than those nitrided before mode jump, which indicates the enhancement of the nitridation. From the spectroscopic ellipsometry, the thickness of nitrided layer was 3–11 nm.