Symmetry of the N-H$_{2}$ complex in GaAsN

The III-N-V alloys have attracted much recent attention because of a large reduction of the band-gap energy that occurs for N concentrations of a few percent. The hydrogenation of these alloys eliminates the effect of N [1]. A previous IR study of the vibrational properties of GaAsN:H showed that the dominant N- and H-containing defect has two weakly coupled N-H modes [2], a finding that is inconsistent with an H$_{2}$* structure proposed in earlier studies. Recent theory [3-5] suggests a defect with C$_{1h}$ symmetry. While uniaxial stress results do not provide vibrational splittings sufficiently large to reveal the symmetry of the N-H$_{2}$ center, new IR absorption experiments performed for the H-wagging modes of GaAsN:H yield results that are consistent with the vibrational properties predicted for the C$_{1h}$ structure [3]. This work is supported by NSF Grant DMR 0403641. \newline [1] A. Polimeni \textit{et al.}, Phys. Rev. B \textbf{63}, 201204(R) (2001). \newline [2] F. Jiang \textit{et al.}, Phys. Rev. B \textbf{69}, 041309(R) (2004). \newline [3] W. B. Fowler \textit{et al.}, Phys. Rev. B \textbf{72}, 035208 (2005). \newline [4] M.-H. Du \textit{et al.}, Phys. Rev. B \textbf{72}, 073202 (2005). \newline [5] G. Ciatto, Phys. Rev. B \textbf{71}, 201301 (2005).