Photoluminescence and Raman properties of MOCVD-grown In0.5 (Ga1-xAlx)0.5P layers under different growth conditions

Two sets of In_0.5(Ga_1-xAl_x)_0.5P/GaAs were prepared by metalorganic chemical vapor deposition, and a combined photoluminescence (PL) and Raman scattering investigation was performed. Variations of PL bands and Raman lines were observed from one set of samples with x~24% and grown with different pressures and dopants. Both the PL and Raman measurements confirmed the Al-compositional variations of the second set of samples, with x~18% and grown under different low pressures and H₂ flows, to be around 1%. It is found that the Raman spectral features are more sensitive to the epitaxial growth parameter variations. The line shape analysis leads to information about the sample crystalline quality and the optimum growth conditions, which is coincident with the qualitative analysis of the growth process. This study offers us a useful way to optimize the parameters to produce high crystalline quaternary InGaAlP materials