1：Experimental Design and Method Selection:

The study employs surface activated bonding (SAB) technologies with a fast atom beam (FAB) of Ar for bonding GaAs to Si substrates. Post-bonding annealing at 300°C is applied to investigate its effects on bonding yield and interface properties. Hard X-ray photoemission spectroscopy (HAXPES) and current–voltage measurements are used for analysis.

2：Sample Selection and Data Sources:

GaAs/AlAs heterostructures on GaAs (100) substrates are prepared by metal organic vapor phase epitaxy and bonded to Si (100) substrates. The junctions are annealed and then placed in a 7.7% HF solution for sacrificial layer etching.

3：7% HF solution for sacrificial layer etching. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a fast atom beam (FAB) system for SAB, atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), and hard X-ray photoemission spectroscopy (HAXPES) at BL47XU facilities in SPring-

4：Experimental Procedures and Operational Workflow:

After bonding, junctions are annealed at 300°C, followed by sacrificial layer etching in HF solution. The exposed surfaces of separated GaAs substrates are characterized using AFM and XPS. Electrical properties of the interfaces are measured using current–voltage techniques.

5：Data Analysis Methods:

The data from HAXPES and current–voltage measurements are analyzed to determine the effects of annealing on the bonding interfaces and the electrical properties of the junctions.