Room temperature electroluminescence in the eye safe region of the spectrum over the range 1.7–2.1 μm is demonstrated from a thulium doped silicon diode. The same room temperature photoluminescence can be attained on a silicon-on-insulator substrate. The emission lines are from the first excited to ground state of the Tm3+ ion, 3F4→3H6. A detailed study has been made to establish the optimum implant and processing conditions for efficient room temperature luminescence. The importance of the correct placement of the thulium ions with respect to the depletion region edge and dislocation loops formed upon boron implantation has been established. Tm3+ has been demonstrated to lase in other systems and is the basis of widely applied, commercial, optically pumped 2 μm lasers. The demonstration of electroluminescence in silicon and luminescence on an SOI platform are necessary prerequisites for the potential development of Tm injection lasers and optical amplifiers. Display omitted •Silicon light emitting diode at 2.1 μm achieved by ion implanting of thulium ions using standard silicon processing.•Room temperature (RT) electroluminescence is demonstrated under forward bias with a low one volt turn on voltage.•RT photoluminescence on an SOI platform is demonstrated, offering potential route towards an electrically pumped Tm laser.•Optimum process for dislocation loops to confine carriers to prevent surface recombination and enable RT luminescence.