Effect of V/III ratio on the optical properties of (3 1 1)A and (3 1 1) B oriented InAlAs/InP heterostructures

•The optical properties of InAlAs/InP structures have been investigated.•We report the effect of V/III ratio and substrate polarity on the optical properties of InAlAs/InP structures.•The type II recombination has shown a strong dependence on V/III ratio and substrate polarity.•PR signals corresponding to Franz-Keldysh Oscillation (FKO) have been observed, in our samples. InAlAs alloy were grown on a InP (3 1 1) substrate with different polarity, by metalorganic chemical vapor deposition (MOCVD) growth. Photoluminescence (PL) and Photoreflectance (PR) measurements have been carried out, in our samples, in order to study the V/III flux ratio effect in type-II heterostructures. It is found that, with increasing excitation power density, the PL line was shifted at higher energy side and no saturation of its associated PL intensity was observed. It is a fingerprint of type II transition emission. Yet, the type II interface recombination has shown a strong dependence on AsH3 overpressure and substrate polarity. Therefore, the arsenic overpressures (V/III) affect the piezoelectric (PZ) field and the As/P exchange in our investigated structures. Indeed, we have observed an opposite behavior of type II energy transition shift from A (Indium In face) to B (Phosphorus P face) polarity substrate in respect to V/III flow ratio variation. This fact has been explained as an atomic terminated surface (In or P) in InP substrate. In the other side, PR signals corresponding to Franz-Keldysh Oscillation (FKO) have been observed, in InAlAs/InP (3 1 1). The analysis of their period has allowed one to determine the value of the PZ field in the samples. This result enables us to extract the V/III ratio and the substrate polarity effect on the type II transition shift, in such heterostructures.