Influence of Growth Temperature and Phosphine Flow on CuPt Type Ordering in InGaP Grown by Chemical Beam Epitaxy

Abstract

ABSTRACTIn this work, In0.5Ga0.5P layers were grown by Chemical Beam Epitaxy on GaAs (001) substrates. A set of samples was grown with temperatures kept in the range of 500°C to 560°C with V/III ratio 15. Another set was grown at 560°C with V/II ratio varied in the range 15 to 35. The evolution of ordering as function of growth temperature and V/III ratio was evaluated by photoluminescence measurements at 77K, Transmission Electron Diffraction (TED) and images using Transmission Electron Microscopy (TEM)-Dark Field. A 48meV reduction in the band gap energy was measured by photoluminescence measurements at 77 K when growth temperature was increased. This result is associated to the occurrence of CuPtB ordering in the InGaP layers observed by TED. The TEM-Dark field examination shows that the ordered domains are larger for samples grown at higher temperaturesA small reduction in band gap, from 1.915eV to 1.902eV, occurs when the V/III ratio is increased from 15 to 35. The TED patterns present diffuse scattering for all samples. For those grown with higher V/III ratio, spots are also observed. TEM-dark field images show that the ordered regions become larger, elongated and inclined; some of them exhibit long range ordering