We have fabricated two-tiered hetero-structures consisting of B delta-doped and P delta-doped Si quantum dots (QDs) embedded in SiO2 on p-and n-Si(100) by repeating Si-QDs formation by low pressure chemical vapor deposition (LPCVD) using pure SiH4 and subsequent surface oxidation and modification by remote plasma, and characterized their electroluminescence (EL) in near-infrared region under DC and AC bias applications to semitransparent Au top-electrodes. The observed EL spectra can be deconvoluted into mainly two components peaked at similar to 1.07 and similar to 1.11 eV, which involve recombination processes through impurity levels. The input power dependence of EL intensities shows that two-tiered structure of P-doped and B-doped Si-QDs is effective to improve EL efficiency while a simple stacking of B-doped Si-QDs is suited to low power operation. This indicates that energy relaxation to lowest quantized levels in charge transfer among valency controlled Si-QDs by impurity doping plays a role on recombination of injected electrons and holes. (C) 2015 Elsevier B.V. All rights reserved.