Influence of exposure to 980 nm laser radiation on the luminescence of Si:Er/O light-emitting diodes

Abstract

Erbium (Er) codoping with oxygen (O) in Si is a well-known method for producing electroluminescent material radiating at 1.54 μm through a 4f shell transition of Er3+ ions. In this work the influence of exposure to 980 nm radiation on the electroluminescence (EL) of reverse biased Si:Er/O light-emitting diodes (LEDs), which give a strong room temperature 1.54 μm intensity, is presented and discussed. All the device layers, including Er/O doped Si sandwiched between two Si0.82Ge0.18 layers, have been grown on silicon on insulator substrates using molecular beam epitaxy and processed to fabricate edge emitting Si:Er/O waveguide LEDs. Electromagnetic mode confinement simulations have been performed to optimize the layer parameters for waveguiding. The temperature dependence of the 1.54 μm EL intensity exhibits an abnormal temperature quenching with a peak near −30 °C, and at −160 °C it has decreased by a factor of 5. However, irradiating the devices with a 980 nm laser gives an enhancement of the 1.54 μm EL intensity, which is more dramatic at low temperatures (e.g., −200 °C) where the quenched EL signal is increased up to almost the same level as at room temperature. The enhancement of the EL intensity is attributed to the photocurrent generated by the 980 nm laser, reducing the detrimental avalanche current.