MOVPE growth of GaAs/Al_xGa_(1-x)As superlattices and their applications inrelative photoelectric devices are reported. Epilayer quantum heterostructures are charac-terized by using cross-sectional transmission electron microscopy (XTEM). In SelfElectrooptic Effect Devices (SEED), the superlaltice interfaces are abrupt and the barrierand well layers keep good uniformity. In some High Electron Mobility Transistors(HEMT), superlattices used as buffer layers smooth out the growing surface roughness.