Role of the V–III ratio and growth rate in decomposition of In0.27Ga0.73P/GaP grown by MOVPE

In this paper, we report on a study of the spinodal-like decomposition of InxGa1−xP grown on (1 0 0) GaP substrates at 740 °C by metalorganic vapor phase epitaxy (MOVPE). We concentrated our efforts on an alloy with the InP mole fraction close to x=0.27, at which the indirect-to-direct band-gap structure crossover occurs. We used the V/III ratio and growth rate for the limitation of diffusion length of adatoms before their incorporation into an epitaxial layer. Transmission electron microscopy (TEM) together with energy dispersive X-ray analysis (EDX) and low-temperature photoluminescence were used to demonstrate that a spinodal-like decomposition of such InGaP layers can partially be suppressed if the V/III ratio is increased from a starting value of 75–350. Next improvement in the quality of the epitaxial layer may be achieved by an increase of the growth rate vg up to value higher as 1.1 μm/h.