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The physical and chemical state of the underlying germanium (Ge) substrate is crucial for the CVD synthesis of high-quality graphene. Here, we investigate the main causes responsible for formation of pit-like defects on Ge (100) and (111) surfaces, their elimination, and their influence on the quality of deposited graphene. Our data provides evidence of pit-like defects formation on Ge surfaces during thermal annealing at T ≥ 800 °C. We establish that the pits are due to preferential evaporation of residual Ge suboxides, and that their efficient removal would result in a pit-free surface. Oxide removal on HF, HCl and HBr treated surfaces is investigated using X-ray photoemission spectroscopy (XPS). The results confirm that in contrast to HF and HCl, HBr effectively eliminates GeO₂ and Ge suboxides, providing pit-free surfaces, which enable CVD growth of high-quality graphene. Hence, we demonstrate that effective …