In0.5Ga0.5P light-emitting diodes (LED’s) that operate in the 660 nm region were fabricated on Si substrates using GaAs buffer layers. InGaP layers were grown by metalorganic-chloride vapor phase epitaxy (MO-chloride VPE), and GaAs layers were grown by metalorganic vapor phase epitaxy (MOVPE) at atmospheric pressure. Red color emission was clearly seen under room light at 20 mA dc injection. The LED operation was stable at 5 kA/cm2 despite the high dislocation density of around 107 cm−2 .