SiGe quantum well infrared photodetectors on pseudosubstrate

In the SiGe system, freedom in the design of quantum well (QW) devices is constrained by the 4.2% lattice mismatch between silicon and germanium. The substitution of the Si substrate by a SiGe pseudosubstrate customized to the respective QW structure’s requirements enables the growth of a $p$-type SiGe QW infrared photodetector featuring interfaces between pure Si and SiGe layers of ultrahigh Ge content for a full exploitation of the band offset between the two materials. Our presented device realizes design concepts for narrowing the spectral response and reducing the noise gain made feasible by the utilization of a $Si0.5Ge0.5$ pseudosubstrate.