Quantum interface between optical photons and long-lived atomic spins have the potential to revolutionize secure communications, ultra-scale sensing, distributed quantum computing, and enhanced metrology. The trivalent rare-earth ion such as erbium (Er³⁺) is a promising candidate for quantum interfaces because of its narrow optical transition in the low-loss telecom band of silica fiber, as well as a long spin coherence time. Current technologies utilized ion-milled bulk crystal and evanescently coupled cavities to enhance Er single photon emission. However, the use of macroscopic bulk substrates of those approaches may limit future scalability. Here, we describe an epitaxial Er³⁺:Y₂O₃ film on silicon platform for scalable quantum devices, enabling quantum spin-photon interfaces based on individual rare-earth qubits. We discuss two systems of (1) Er³⁺:Y₂O₃ membranes in a fiber microcavity and (2) heterogeneous rare-earth/silicon nanophotonic cavities fabricated using standard CMOS technology towards proof-of-concept demonstrations of a telecom quantum interconnect system. Enhanced emission and long-lived coherence of erbium dopants in an array of these devices will extend the range of quantum communication networks for a host of quantum information applications. We foresee this epitaxial rare-earth on silicon platform will expedite and expand large scale, high performance quantum photonic functionalities including quantum memories, transducers and atomic scale senso