A scanning tunneling microscope (STM) with an electrically conductive and optically transparent probe was used to study electroluminescence induced by tunneling electrons from erbium oxide (Er3O3) deposited on SiO2∕Sið100Þ. Erbium was primarily incorporated into SiO2 on silicon substrate to create impurities and overcome a high band gap. Subsequently, emissions of photons in the visible/near-infrared region, because of the excitation of higher Er states, are realized electrically without the need to apply high voltage. The STM-induced photon emission exhibits an asymmetric character with respect to the applied bias, which is explained by the direct recombination and impact ionization processes. The observed electroluminescence spec- trum was decomposed to identify single inter-band transitions that could be related to erbium states. STM-induced electron emission measurements were also performed, revealing a band gap of around 2.8 eV. This corresponds to the x ¼ 0.91 rate factor of the SiOx layer created during the annealing process on silicon. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.JNP.6.063503)