MG-DOPED GREEN LIGHT-EMITTING-DIODES OVER CUBIC (111)MGAL2O4 SUBSTRATES

We report on the fabrication and characterization of Mg-doped green li ght emitting diodes (LEDs) over cubic (111) MgAl2O4 substrates with a very strong impurity band electroluminescence. A 0.2-micron-thick Mg-d oped In0.13Ga0.87N layer was used in the active region of mesa type LE D structures. The emission spectrum was centered at 510 nm (green) wit h 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 mu W and 0.3%. The origin of green light in the Mg-doped In0.13Ga0 .87N layer has also been studied by time resolved photoluminescence. O ur 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. (C) 1997 American Institute of Physics.