p-n Ga0.65In0.35P homostructure light-emitting diodes grown on GaAs0.7P0.3 substrates have been fabricated by low-pressure metalorganic vapor-phase epitaxy. The growth and characterization of undoped, Si-, and Zn-doped layers are described in detail. The optimum growth condition to grow the high-quality Ga0.65In0.35P epitaxial layers is at the growth temperatures of 700-740-degrees-C and V/III ratios of 100-200. The strongest photoluminescence peak intensity occurs at 2 x 10(18) and 7 x 10(17) cm-3 for electron and hole concentrations, respectively. Diodes fabricated from the p-n homostructure are characterized by current-voltage measurement, electroluminescence, and external quantum efficiency. A forward-bias turn-on voltage of 1.68 V with an ideality factor of 2.5 and a breakdown voltage of 9 V are obtained from the current-voltage measurements. The emission peak wavelength and full width at half-maximum of electroluminescence are around 610 nm and 79 meV at 20 mA. The external quantum efficiency of the uncoated diode is about 0.015%.