Investigation of the surface treatment of GaAsSb/Si using current– and capacitance–voltage measurements

In this study, the effects of surface treatments on the bonded interface between novel III–V absorber material GaAs0.51Sb0.49 latticed-matched to InP and Si are experimentally investigated. Both hydrophobic- and hydrophilic-based surface treatments are performed on target Si substrates prior to transfer-printing-based bonding of GaAsSb. Both current–voltage and capacitance–voltage measurements on these devices suggest that interface oxides, which contribute to robust bonding between GaAsSb and Si, block photoinduced charge transport. Unlike hydrophilic O2 plasma treatment, hydrophobic HF wet etching on Si produces an optimized interface with less defects and facilitates charge transport. After the HF-bonded sample was treated under vacuum right before transfer, the resulting p–i–n photodiodes based on p-GaAsSb/i-GaAsSb/n-Si exhibits device performance comparable to monolithic GaAsSb diodes directly grown on InP substrates. Under 1550 nm illumination, the printed diode outputs a VOC of 230 mV, while the monolithic GaAsSb diode outputs a VOC of 320 mV.