The Al0.13Ga0.87As epilayers were regrown by metalorganic chemical vapor deposition (MOCVD) on different AI0.26Ga0.74As substrate layers. It was found that the quality of regrown A10.13Ga0.87As layers were significantly improved when a Se-doped Al0 26Ga0.74As substrate was used. Electrochemical C-V profile showed that no oxide formation and impurity incorporation at the regwon interface. Low-temperature (14.9 K) photoluminescence showed that the full width of half maximum (FWHM) of the bound exciton peak is as low as 4.51 meV. We attributed this improvement to the Se-passivation effect at the surface of Se-doped A10.26Ga0.74As substrate-layers. Results show that Se will delay the formation of native oxide to achieve the better quality of regrown AlGaAs layers.