Interfacial and optical properties of YO_xN_y gate dielectrics at different deposition temperatures

YO_xN_y dielectric films were grown by rf-magnetron sputtering on a n-Si(1 0 0) substrate at different deposition temperatures from 300 to 550 °C. The interfacial properties of YO_xN_y films with different deposition temperatures were investigated using x-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. It was found that an interfacial layer of yttrium silicate was formed between the YO_xN_y films and the Si substrate during deposition, and the higher the deposition temperature, the thicker the interfacial layer. The x-ray diffraction analysis shows that the phase transition of the YO _xN_y films occurs at substrate temperatures between 400 and 550 °C. The spectroscopic ellipsometry results indicate that the deposition temperature has a strong effect on the optical properties of the YO _xN_y films. The band gap was found to shift to higher energy at higher deposition temperature, which is likely due to the change in the crystalline structure of the YO_xN_y films.