| dc.description.abstract | Shortwave infrared (SWIR) light, which is invisible, exhibits low scattering and low water absorption at 1350 nm and 1550 nm wavelength ranges. It can transmit silicon to resolve details that are not analyzed by visible light. Therefore, the demand for SWIR sensors has significantly increased in the market. However, the multilayer design for SWIR filters is too thick to achieve the advancements of miniaturization and integration. A high refractive index material with low absorption is necessary to develop SWIR filters. In this study, germanium and germanium oxide are used as high and low refractive index materials, respectively, to aim their characteristics and practical applications.
Germanium is the first-generation semiconductor material, however there are less research about its optical properties. In this experiment, reactive high power impulse magnetron sputtering (HiPIMS) is chosen as the deposition method for germanium thin films. The experiment consists of three parts. Firstly, the process parameters are optimized by adjusting the fabricated temperature, power, and HiPIMS duty cycle to improve optical properties. Secondly, the gas flux is modulated by controlling the flow rates of hydrogen and oxygen, to adjust the hydrogen and oxygen doping concentration in the germanium thin films and then to evaluate the film properties such as the refractive index and extinction coefficient of germanium and germanium oxide. Lastly, based on the results from the previous two parts, multilayer SWIR filters are designed and fabricated in the same chamber and target materials with different working gases to achieve the narrowband pass filters for the transmission bands at 1550 nm and 1350 nm. | en_US |