Mesa-structured AlGaAsSb APD: dark current and noise analysis

• A low-noise SAGCM InGaAs/AlGaAsSb APD operating at 1550 nm was successfully fabricated with a double-mesa structure. • The double-mesa structure reduces the electric field at the multiplication region edge by nearly 100 kV/cm compared to single-mesa, suppressing trap-assisted tunneling and reducing dark current by up to four times. • The AlGaAsSb APD exhibits an exceptionally low excess noise factor with a k-value of approximately 0.014, outperforming traditional multiplication materials. • This work validates the potential of AlGaAsSb APDs for achieving both low dark current and low noise, promising for applications in optical communication and LIDAR.