Unlocking Germanium Potential: Stabilization Strategies Through Wet Chemical Functionalization

Germanium (Ge) has long been recognized for its superior carrier mobility and narrower band gap compared to silicon, making it a promising candidate in microelectronics and optoelectronics. The recent demonstration of good biocompatibility, combined with the ability to selectively functionalize its surface, establishes the way for its use in biosensing and bioimaging. This review provides a comprehensive analysis of the most recent advancements in the wet chemical functionalization of germanium surfaces. Wet chemical methods, including Grignard reactions, hydrogermylation, self-assembled monolayers (SAMs) formation, and arylation, are discussed in terms of their stability, surface coverage, and potential for preventing reoxidation, one of the main limits for Ge practical use. Special emphasis is placed on the characterization techniques that have advanced our understanding of these functionalized surfaces, which are crucial in the immobilization of molecules/biomolecules for different technological applications. This review emphasizes the dual functionality of surface passivation techniques, demonstrating that, in addition to stabilizing and protecting the active material, surface functionalization can impart new functional properties for germanium-based biosensors and semiconductor devices.