Study on Infrared Absorption Characteristics of Ti and TiNx Nanofilms

Infrared detector has a wide range of applications. To fabricate an IR detector with good sensitivity, an efficient IR absorber is needed. In this paper, we theoretically and experimentally investigated the absorption characteristics of Ti, multi-layer structured Ti-SiO2 and TiNx-SiNx nano films. The multi-layer structured TiNx-SiNx films with different nitrogen contents and Ti nano films with different thicknesses were deposited by ebeam sputtering. Their IR absorption characteristics were investigated by Fourier Transform Infrared Spectrometer. For single nano Ti film, 35% absorptivity was obtained at a wavelength of 1.67μm when the film thickness was 15.3nm. A better IR absorption characteristic was achieved for multi-layer structured Ti-SiO2 nano film. In this structure, an absorption peak of appears at a wavelength of 9.5μm. Compared with the absorption behavior of single SiNx film, an additional nano TiNx film obviously improved IR absorption at a wider band. And a maximum IR absorptivity of 27% was obtained at the wavelength of 14μm.