Resonant Photocurrent at 1550 nm in an Erbium Low-Doped Silicon Transistor at Room Temperature

We report on the photocurrent induced by 1550 nm laser irradiation in a Er-doped micron-scale silicon transistor. The erbium defects, activated in the channel of the transistor thanks to oxygen codoping, make it possible to observe a resonant photocurrent at telecom wavelength and at room temperature by using a supercontinuum laser source working in the $\mu\mathrm {W}$ range. By exploiting a back-gate, the transistor is tuned to exploit only the electrons lying in the Er-O states. We estimate a relatively small number of photoexcited atoms $(\sim 4\times 10^{4})$ making Er-dpoed silicon a candidate for designing resonance-based frequency selective single photon detectors at 1550 nm for quantum communications.