Abstract
The purpose of this study is to investigate the optical properties of chromium oxide film in visible light and near infrared (NIR) region, to obtain the best absorbing effect (high extinction coefficient) at 650 nm and best filter effect (low transmittance) at 1400 nm. It can be applied in monolayer absorbing film and neutral density filter (ND filter). The chromium oxide film is deposited by electron-beam evaporation system. The reflectance and transmittance are measured by spectrometer, then numerical method is used to analyze optical constants. The structure is detected by SEM and XRD; the composition is detected by XPS and sheet resistance is measured by four-point probe. In this study, the process parameters include process pressure (oxygen flow rate), process temperature and ion beam assisted deposition (IAD). For the process pressure, the metal phase decreases and the transmittance increases with the oxygen flow rate. For the process temperature, there is a slight decrease in transmittance when the process temperature is 200 ℃, and columnar crystals can not be found in the structure. For the IAD, the transmittance increases after the Ar or O2 IAD process is used, the O2 IAD process is more obvious. The columnar structure in the film under O2 IAD process is less than the film without O2 IAD process, so the density of film deposition has increased. The results show that the best parameter for the process pressure is 1×〖10〗^(-3) Pa; for the process temperature is 200 ℃, without IAD process. At 650 nm, the extinction coefficient is 0.048; at 1400 nm, the transmittance is 68%.