Microstructure, optical properties, and optical resonators of Hf1-xTixO2 amorphous thin films

TitleMicrostructure, optical properties, and optical resonators of Hf1-xTixO2 amorphous thin films
Publication TypeJournal Article
Year of Publication2016
AuthorsJiang, F, Bi, L, Lin, H, Du, Q, Hu, J, Guo, A, Li, C, Xie, J, Deng, L
JournalOptical Materials Express
Pagination1871 - 1880
Date Published2016/06/01/
ISBN Number2159-3930
Keywordsanatase tio2, devices, hfo2, microring resonators, oxidation, wave-guides

We report Hf1-xTixO2 (0< = x< = 1) thin films (HTO) as index tunable and highly transparent materials for ultraviolet to near infrared integrated photonic devices. By varying the Ti concentration, reactive cosputtered HTO thin films on thermal oxidized SiO2 on Si substrates show continuously tunable optical band gaps from 3.9 eV to larger than 5 eV. The film refractive index monotonically increases with Ti concentration, varying from 1.8 to 2.4 in the visible to near infrared wavelength range. Micro-disk amorphous HfO2 resonators on SiO2/Si substrates are fabricated using sputtering and lift-off method. A loaded quality factor of similar to 15800 at around 1580 nm wavelength is achieved in HfO2 disk resonators with diameters of 100 mu m. The propagation loss of the HfO2 ridge waveguide is estimated to be 2.5 cm(-1). The wide optical transparency range, variable index of refraction, low temperature, CMOS-compatible fabrication capability, and high optical transparency make amorphous HTO thin films promising candicates for integrated photonic applications. (C) 2016 Optical Society of America

Short TitleOpt. Mater. Express