Progress in the emergent field of topological superconductivity relies on synthesis of new material combining superconductivity, low density, and spin-orbit coupling (SOC). Theory indicates that the interface between a one-dimensional semiconductor with strong SOC and a superconductor hosts Majorana-modes with nontrivial topological properties. We discuss the recent developments in epitaxial growth of Al on InAs nanowires was shown to yield a high quality superconductor-semiconductor system with uniformly transparent interfaces and a hard induced gap, indicted by strongly suppressed subgap tunneling conductance. We have developed a two-dimensional (2D) surface InAs quantum wells with epitaxial superconducting Aluminum, yielding a planar system with structural and transport characteristics as good as the epitaxial nanowires. The realization of 2D epitaxial superconductor-semiconductor systems represent a significant advance over wires, allowing extended networks via top-down processing. We present our recent developments in materials synthesis and growth of these density-controlled surface 2D electron-gases and demonstrate Josephson junctions with highly transparent contacts. These developments have lead to unprecedented control over proximity effect in semiconductors where electron densities can be tuned using a gate voltage. We discuss potential applications of this new material system that can serve as a platform for low power circuits, gate-based qubits as well as exploring topological superconductivity for computation.