Optimal Design and Noise Analysis of High-Performance DBR-Integrated Lateral Germanium (Ge) Photodetectors for SWIR Applications

This work presents the high-performance Si/SiO2 distributed Bragg reflector (DBR)-integrated lateral germanium (Ge) p-i-n photodetectors (PDs) for atmospheric gas sensing and fiber-optic telecommunication networks in the short-wave infrared (SWIR) regime. In addition, this study also proposes an optoelectronic compact small-signal noise equivalent circuit model (SSNECM) of the designed device to compute the noise performance at the detectors' output. Various figure-of merits including current under dark and illumination, responsivity, detectivity, bandwidth, and the noise of the proposed device are estimated at the room temperature (RT) for an incident optical power of 0.5 μW. Furthermore, the impact of width and height scaling on dark current, responsivity, and bandwidth are investigated to optimize the proposed device. The validation of the proposed model is done by comparing various parameters including dark current, responsivity, and detectivity of the designed device with other Ge PDs. The estimated results show the reduced trade-off between responsivity and bandwidth of the designed device. At λ=1550 nm, the proposed device achieves a high detectivity and SNR of >2×1011Jones and 120 dB (at 3 THz), respectively, with the bias voltage of -2V. These encouraging results pave the path for the future development of low-noise and high-speed detectors.