Demonstration of Planar Geometry PIN Photodetectors with GeSi/Ge Multiple Quantum Wells Hybrid Intrinsic Region on a Ge-on-Insulator Platform

In this article, the first demonstration of planar geometry Ge PIN short-wave infrared (SWIR) photodetectors (PDs) on a germanium-on-insulator (GOI) platform has been presented. The intrinsic layer Ge contains four Ge0.86Si0.14 multiple quantum wells (MQWs). The structural characteristics, material quality, and interface integrity of the PDs were investigated by using high-resolution transmission electron microscopy (HR-TEM) and high-resolution X-ray diffraction (HR-XRD). The devices exhibited a 3.12 mA/cm2 dark current density and a low bulk leakage current density of 0.94 mA/cm2 at −1 V. The integration of tensile-strained GeSi/Ge MQWs significantly enhanced the responsivity while maintaining a relatively lower dark current density, thereby broadening the spectral response range to 1700 nm. The notably high responsivities at 1310 and 1550 nm are 0.99 and 0.78 A/W, respectively, corresponding to external quantum efficiencies (EQEs) of 93.7 and 62.4%. Furthermore, the optical confinement effect inherent to this type of GOI structure contributed to a pronounced enhancement in the responsivity across the O, E, S, and C bands, with a peak responsivity of 1.11 A/W at 1475 nm. These findings underscore the potential of CMOS-compatible GOI platforms with MQWs hybrid intrinsic regions for diversified optoelectronic applications. Additionally, the demonstrated planar geometry Ge PIN PDs on insulator substrates exhibit excellent prospects for high-resolution SWIR imaging, which pave the way for advancements in next-generation photonic and sensing technologies.