<p>Germanium–silicon–germanium (Ge/Si<sub>x</sub>Ge<sub>1-x</sub>) heterostructures have emerged as a prominent platform for high-mobility electronic devices and hole-spin–based quantum technologies. In this work, we present an <em>ab initio</em> study of strained germanium, demonstrating that biaxial compressive strain in a Ge quantum well strongly alters the valence-band structure. Specifically, the strain lifts the heavy-hole/light-hole degeneracy and modifies the effective masses (significantly enhances hole mobility). Our findings offer a comprehensive theoretical description of the combined effects of strain and quantum confinement on the valence bands of Ge quantum wells, providing a solid foundation for predictive modeling of Ge-based high-mobility electronics and hole-spin qubits.</p>
