Wafer-scale growth of 2D SnSx hybrid films on germanium by atomic layer deposition for broadband photodetection

Two-dimensional transition metal chalcogenides (2D-TMCs) are promising materials with unique optical and electrical properties compared to bulk materials. Although the exfoliated/CVD-growth 2D-TMCs have superior properties, they have a limitation for wafer-scale processes and applications in integrated circuits (ICs). Herein, we report the fabrication of wafer-scale 2D hybridized tin chalcogenide (SnSx) on a germanium (Ge) substrate using an atomic layer deposition process, followed by a thermal annealing process to form 2D-SnSx. 2D-SnSx consists of a hybrid structure of parallel 2D-SnS2 and tilted SnS on a Ge (100) substrate, enabling bandgap lowering and intrinsically p-type doping. As a result, our broadband photodiode with a p-SnSx/n-Ge heterostructure showed a specific responsivity of 0.41 and 0.24 A/W at wavelengths 532 and 1550 nm, respectively. This work demonstrates the potential for wafer-scale 2D-TMC-based facile ICs on the Ge substrate.