  Superconductor/semiconductor hybrid devices have attracted increasing
interest in the past years. Superconducting electronics aims to complement
semiconductor technology, while hybrid architectures are at the forefront of
new ideas such as topological superconductivity and protected qubits. In this
work, we engineer the induced superconductivity in two-dimensional germanium
hole gas by varying the distance between the quantum well and the aluminum. We
demonstrate a hard superconducting gap and realize an electrically and flux
tunable superconducting diode using a superconducting quantum interference
device (SQUID). This allows to tune the current phase relation (CPR), to a
regime where single Cooper pair tunneling is suppressed, creating a $\sin
\left( 2 \varphi \right)$ CPR. Shapiro experiments complement this
interpretation and the microwave drive allows to create a diode with 100%
efficiency. The reported results open up the path towards integration of spin
qubit devices, microwave resonators and (protected) superconducting qubits on a
silicon technology compatible platform.
