1：Experimental Design and Method Selection:

The study uses metal organic vapor phase epitaxy (MOVPE) with a two-step growth technique involving low-temperature buffer layer and high-temperature main layer growth on miscut Ge substrates to reduce anti-phase boundaries.

2：Sample Selection and Data Sources:

Single-side polished, 6° miscut (001) Ge substrates were used. Samples were prepared with varying AsH3 pre-flow durations (0, 3, 6 minutes) and V/III ratios (10, 21, 42) for the GaAs buffer layer.

3：List of Experimental Equipment and Materials:

Equipment includes AIXTRON 200/4 RF-S horizontal flow MOVPE system, Luxtron 880 nm reflectometer, Rigaku SmartLab diffractometer, Witec Confocal Raman Microscopy system, HeCd laser, Hamamatsu PMT detector, monochromator, and He closed cycle cryostat. Materials include trimethylgallium (TMGa), arsine (AsH3), hydrogen carrier gas, and Ge substrates.

4：Experimental Procedures and Operational Workflow:

Ge substrates were thermally desorbed at 710°C in H2 for 5 minutes. AsH3 pre-flow was applied at 535°C for specified durations. GaAs buffer layers were grown at 535°C with varying V/III ratios, followed by high-temperature GaAs main layer growth. In-situ optical reflectance, HRXRD, Raman spectroscopy, and low-temperature photoluminescence measurements were performed.

5：Data Analysis Methods:

Data were analyzed using in-situ reflectance for surface quality, HRXRD for crystalline quality (FWHM and peak intensity), Raman for structural quality (TO/LO intensity ratio), and PL for optical quality (peak intensity and FWHM).