The electroluminescence (EL) properties of prospective cubic gallium nitride p–n junctions grown by molecular beam epitaxy (MBE) are studied. The samples were deposited on a 3 μm thick silicon carbide layer grown by chemical vapor deposition (CVD) on an n⁺ silicon substrate. At room temperature, visible and UV electroluminescence are obtained for V = 2.5 V under dc conditions. At low temperatures only UV luminescence is observed. This low temperature luminescence is mostly given by shallow donor–acceptor and band edge transitions. The activation at increasing temperatures of a visible green‐blue electroluminescent band could be explained by the thermal activation of Mg deep states. Our results indicate that the MBE cubic gallium nitride material is a promising alternative for the fabrication of light emitters on silicon compatible substrates.