We report on near-field optical observations of surface-plasmon-mediated light emission in electrically biased metal-insulator-semiconductor (MIS) tunnel junctions fabricated from Au and p -type Si with a native oxide layer as the tunneling barrier. Our junctions exhibit stable broadband macroscopic light emission in the visible spectrum. Inspection of the optical near-field reveals highly localized hot spots due to local plasmon excitation and scattering, which are investigated with spectral distinction. Such MIS tunneling junctions are compatible with common complementary metal-oxide semiconductor technology and thus open up an interesting route toward the development of novel integrated optoelectronic and plasmonic devices.