The local structure, infrared phonon modes and the origin of the dielectric constant in La2Hf2O7 thin film
National Synchrotron Radiation Laboratory, University of Science and Technology of China Hefei, Anhui, 230029, China
2 Department of Technology and Physics, Zhengzhou University of Light Industry - Zhengzhou, Henan, 450002, China
3 Institute of Microelectronics of Chinese Academy of Science - Beijing, 100029, China
Accepted: 1 February 2012
The local structure and dielectric properties of crystalline and amorphous La2Hf2O7 (LHO) thin film were studied by X-ray absorption spectroscopy and infrared spectroscopy. The basic infrared phonon modes with most contributions to the static dielectric constant of crystal LHO are preserved, which causes the considerable value of the static dielectric constant in the amorphous thin film. The preservation of the main infrared phonon modes in the amorphous thin film is because it has similar the nearest local structures around Hf and La atoms as the crystal LHO. This inheritance of the local structural and vibrational features of the crystal phase is the origin of the dielectric constant of the LHO thin film.
PACS: 77.55.-g – Dielectric thin films / 61.05.cj – X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. / 63.22.-m – Phonons or vibrational states in low-dimensional structures and nanoscale materials
© EPLA, 2012