Reduction of spontaneous surface segregation in (InP)(2)/(GaP)(2) quantum wells grown on tilted substrates

We have studied the growth mechanism of (InP)(2)/(GaP)(2) short-period supe rlattices (SPS) and In(0.5)Gao(0.5)P quantum wells grown on tilted substrat es using solid-source molecular beam epitaxy (SSMBE). Both the (InP)(2)/(Ga P)(2) SPS and In0.5Ga0.5P quantum wells show blue shifts of photoluminescen ce (PL) wavelengths when the substrate's tilting angle is increased. The bl ue shift is more prominent in the SPS structure than in the In0.5Ga0.5P qua ntum wells. By comparing FL, polarized PL spectra and transmission electron micrographs, we confirm that the ordering effect exists in both the (InP)( 2)/(GaP)(2) SPS and In0.5Ga0.5P quantum wells when the substrate tilt angle is small, and can be greatly reduced when the substrate lilt angle is incr eased. We believed that the height and density of steps on substrates with larger tilt angles repress the segregation of group III adatoms.