This paper reviews our recent progress on silicon (Si) pn junction light emitting diodes with locally doping engineered carrier potentials. Boron implanted Si diodes with dislocation loops have electroluminescence (EL) quantum efficiency up to 0.12%, which is two orders of magnitude higher than those without dislocations. Boron gettering along the strained dislocation lines produces locally p-type spike doping at the dislocations, which have potential wells for bounding spatially indirect excitons. Thermal dissociation of the bound excitons releases free carriers, leading to an anomalous increase of the band to band luminescence with increasing temperature. Si light emitting diodes with external quantum efficiency of 0.2% have been also demonstrated by implementation of pnpn modulation doping arrays.