**4. Conclusion**

In summary, InAlAs/InP type-II heterostructures with a varying V/III ratio grown successfully on (311) A or B Fe-doped InP substrates by MOCVD were investigated and the optical properties of the grown structures were examined. The different optical properties of the samples grown on (311) A or B substrates are caused from the difference of their plane-bonding configurations. In particular, the optical properties of InAlAs-InP interface display a significant reliance on AsH3 overpressure and substrate polarity. PL and PR measurements indicated that substrate orientation and V/III ratio molar have an important impact on the quality of inverted interface. The measurements of excitation power density PL confirm the intrinsic transition of type II. A red shift of the type-II transition was noted at low temperature with an increased V/III ratio of the polarity A samples and a blue shift for polarity B samples. These findings could be clarified by the opposite field of PZ at the heterostructures of InAlAs/InP resulting from distinct polarity of the InP substrate. We acquired the InP field built-in PZ in the heterostructures from an assessment by the FKO. We have made an explanation of the transition shift from these values. Additionally, the temperature variety shows an anomalous S-shaped dependence that is typical of carrier localization in the material. The optical properties are significantly influenced by the PZ field in our samples. Therefore, the impact of the PZ field on the design and manufacture of greater quality instruments should be taken into consideration.
