High-Gain Ge/Si Avalanche Photodetector With Stable Operation Temperature Up to 500 K

In this study, a novel approach for fabricating Ge/Si APDs using high-vacuum in-situ sputtering bonding technology is presented. By introducing a 3 nm thick amorphous Si (a-Si) at the Ge/Si bonded interface, the lattice mismatch is effectively mitigated, significantly improving the bonding quality and enhancing carrier transport efficiency. Through a combination of sputtering, etching, and photolithography techniques, Ge/Si APDs with diameters of 70 μm and 100 μm are successfully fabricated, incorporating a separation absorption charge multiplication layer structure. It is demonstrated that the Ge/Si APDs exhibit exceptional performance under 1310 nm wavelength illumination, with gains reaching 4.8×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> and 1.1×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> for the 70 μm and 100 μm devices, respectively. Moreover, the devices maintain stability at extreme temperatures up to 500 K, highlighting their potential for weak light detection in harsh environments.