The growth and characterization of AlGaInP double-heterostructure orange light-emitting diodes (LEDs) grown on n- and p-GaAs misoriented substrates by low-pressure metallorganic vapor-phase epitaxy are presented. Zinc and silicon are used as p- and n-type dopants for AlGaInP, respectively. The device performance is found to be strongly dependent on the doping concentration in both upper and lower cladding layers for the p-substrate LEDs. However, for the n-substrate LEDs, the strong dependence is only found on the doping concentration in the upper cladding layer. The degradation of device performance with increasing doping concentration in the cladding layer is thought to be due to the light absorption by deep levels. After optimizing the doping concentration in the LEDs, better LED performance can be obtained by using the p-type substrate. This demonstrates the feasibility of fabricating AlGaInP LEDs grown on p-GaAs substrates.