Spinodal-like decomposition of InGaP epitaxial layers grown on GaP substrates

The spinodal-like decomposition of In_xGa_1−xP epitaxial layer prepared by low-pressure metallorganic vapour phase epitaxy was studied by means of photoluminescence and transmission electron microscopy. Epitaxial layers were grown on GaP substrates at T_g = 740 °C and reactor pressure of 20 mbar. We show that presence of spinodal-like decomposition occur at samples with InP mole fraction higher as x = 0.2 and V/III ratio of 75. The low-temperature photoluminescence spectra shows that in partially decomposed samples a characteristic broad band occurred close to 1.985 eV. An increase in the V/III ratio up to a value of 350 suppressed the decomposition, and PL signal with only one narrow transition was obtained.