High-absorbance resonant-cavity-enhanced free-standing Ge photodetector for infrared detection at 1550 nm wavelength

A novel free-standing resonant-cavity-enhanced (RCE) Ge thin-film absorber is designed with a bottom distributed Bragg reflector (DBR) for infrared photodetection at 1550 nm wavelength based on Si substrate. The structure offers high degree of freedom in optimizing the number periods, layer arrangement, and thickness each DBR. SiO2/Si DBR that compatible processing technology used thin film to construct RCE structure. Based our theoretical study, SiO2 low-index must be placed next utilize large difference refractive indices between achieve reflectance In this design, can reach an absorbance 85.90% three periods antireflective oxide top surface layer. Without layer, increased 99.17%. design paves way high-responsivity photodetectors Si-based photonic systems.