OPTICAL CHARACTERIZATION OF INP/INALAS/INP INTERFACES GROWN BY MOVPE

The InAlAs alloy grown on InP has a great technological importance for applications to both high-speed devices and optoelectronic systems. In this paper, we present results of low-temperature optical studies carried out on InP/InAlAs/InP heterostructures. Samples were grown by the atmospheric pressure metal organic vapor phase epitaxy (MOVPE) technique at 650-degrees-C, using TMAl, TMIn, PH3 and AsH3 sources. The interface formed by growing InAlAs on InP is called direct interface. The interface formed by growing InP on InAlAs is called the inverse interface. Photoluminescence (PL) experiments were carried out on these samples. The type II nature of the direct interface leads to a strong interface PL peak at 1.2 eV. This PL is very sensitive to the quality of the heterostructure and could be used as a probe for the MOVPE growth parameters. More surprising is the 1.3 eV PL peak which we ascribe to the inverse interface. From its dependence upon the excitation power (energy and full width at half maximum), it is clear that it originates from the interface recombination. We show that the two heterointerfaces InP/InAlAs and InAlAs/InP are not equivalent in the case of our MOVPE grown samples.