AlGaInP growth parameter optimisation during MOVPE for opto-electronic devices

For (AlxGa1−x)1−yInyP growth on GaAs for opto-electronic devices in metal-organic vapour phase epitaxy an accurate control of the aluminium content x and of the indium content y is crucial. Therefore, we applied an in situ curvature sensor to determine the lattice matching (i.e. indium content y) of the growing material. It was found that AlGaInP which is lattice matched at room temperature is tensile strained at growth temperature leading to a concave substrate bowing during growth. Overgrowing AlGaInP with GaAs an additional change in wafer bowing was observed presumably caused by indium segregation which is supported by a simulation of the measured data. Furthermore, for an accurate in situ determination of the aluminium content x and of the growth rate a high-temperature database for the optical constants n and k of lattice matched AlGaInP was established. Taking reflectance transients during growth of AlGaInP layers a numerical fit to the data enables a determination of the growth rate and the aluminium content.