We report on the fabrication and characterization of Mg-doped green light emitting diodes (LEDs) over cubic (111) MgAl2O4substrates with a very strong impurity band electroluminescence. A 0.2-micron-thick Mg-doped In0.13Ga0.87N layer was used in the active region of mesa type LED structures. The emission spectrum was centered at 510 nm (green) with a full-width at half-maximum of 60 nm. At a forward bias current of 20 mA the output power and the external quantum efficiency were about 200&mgr;W and 0.3&percent;. The origin of green light in the Mg-doped In0.13Ga0.87N layer has also been studied by time resolved photoluminescence. Our study demonstrates impurity band LEDs to be a viable alternative to band edge emission green LEDs with high indium mole fractions in the active region. ©1997 American Institute of Physics.