The absorption enhancement effect of metal gratings integrated Silicon-based Blocked-Impurity-Band (BIB) terahertz detectors

High-sensitivity Terahertz (THz) detection technology is widely researched for its potential applications in astronomical observation, human security check, weak signal biomacromolecule detection, etc. In this work, a novel THz detector based on metal gratings/Si-BIB hybrid structure is theoretically simulated and successfully fabricated. From FDTD simulation results, the optical field is localized in the absorbing-layer region due to the waveguide resonance effect of metal gratings with 7μm period, 5μm depth and 2/7 duty ratio. Then, the experimental results show that its spectral response is 223% higher than that of the device without metal gratings at the peak wavelength of 17μm. Our work successfully proposed a practical hybrid structure device for the biomacromolecule detection application as well as the weak signal detection in other THz applications.