Simulation model of an enhanced design with high-efficiency, low dark current 1550 nm GeSn/SiGeSn QWPD based on a charge barrier and Bragg reflector

The most common QWIPDs are built with high-cost III-V materials like InGaAs. In this work, we try to have a cheaper alternative based on SiGe QWs. A new structure for the 1550 nm QWPD, to our knowledge, is introduced. The performance of the proposed device is optimized using two methods. The first one is by adding a charge barrier after the last QW. This barrier works to block the dark current charges. The second method is by adding a Bragg reflector under the QWs region to compensate for the limited number of QWs due to the lattice mismatch between silicon and germanium. The results show a significant improvement for both dark current and detection probability. The dark current is decreased to one-fifth, while the PDP is doubled.