Structural and electrical properties of grafted Si/GaAsSb heterojunction

The short-wave infrared (SWIR) wavelength, especially 1.55 μm, has attracted significant attention in various areas such as high-speed optical communication and LiDAR systems. Avalanche photodiodes (APDs) are a critical component as a receiver in these systems due to their internal gain, which enhances the system performance. Silicon-based APDs are promising since they are CMOS compatible, but they are limited in detecting 1.55 μm light detection. This study proposes a p-type Si on n-type GaAs0.51Sb0.49 (GaAsSb) lattice matched to InP substrates heterojunction formed using a grafting technique for future GaAsSb/Si APD technology. A p+Si nanomembrane is transferred onto the GaAsSb/AlInAs/InP substrate, with an ultrathin ALD-Al2O3 oxide at the interface, which behaves as both double-side passivation and quantum tunneling layers. The devices exhibit excellent surface morphology and interface quality, confirmed by atomic force microscope and transmission electron microscope. Also, the current–voltage (I–V) of the p+Si/n−GaAsSb heterojunction shows the rectifying characteristics with an ideality factor of 1.8. The I–V tests across multiple devices confirm high consistency and yield. Furthermore, the x-ray photoelectron spectroscopy measurement reveals that GaAsSb and Si are found to have type-II band alignment with a conduction band offset of 50 meV, which is favorable for the high-bandwidth APD application. The demonstration of the GaAsSb/Si heterojunction highlights the potential to advance current SWIR PD technologies.