Photon detection and emission of epitaxial Ge on Si with potential applications in microwave photonic filters

Microwave photonic filter requires high-speed Radio frequency (RF)-optical and optical-RF signal conversion. Light sources and photo-detectors (PDs) are indispensible for such conversions. Monolithic integration of functions of photon emission and detection is demonstrated using epitaxial Ge on Si. The fabricated waveguided PD shows a high bandwidth of 10 GHz with the responsivity of 0.8 A/W and dark current of 150 nA at -1V. The photoluminescence (PL) properties of P-implanted Ge are studied, and an improved annealing process is demonstrated to enhance the light emission by 1 order. Electroluminescence (EL) is obtained from the waveguided n⁺-Ge light-emitting diode (LED), and the emitted power has been studied as a function of injected current. The successful demonstration of both waveguided PD and LED on single Si chip would be attractive for fabricating a compact size microwave photonic filter with low cost and high integrity.