On the true optical properties of zinc nitride

Refractive index (n) and extinction coefficient (k) of Zn3N2 layers deposited by radio-frequency magnetron sputtering at temperatures (T-s) between 298 and 523K were determined by spectroscopic ellipsometry. Results showed strong variations of the apparent optical constants with T-s and time attributed to surface effects. Resonant Rutherford backscattering and spectroscopic ellipsometry confirmed the formation of a ZnO surface layer provoked by the ambient exposure. Samples grown at low T-s presented the lowest surface roughness and exhibited 2.0 < n < 2.8 and 0.6 < k < 1.0 in the 1.5-4.5 eV energy range. The extracted n and k values accurately reproduced the reflectance properties. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3663859]