Excitation Power Control of Circular Polarization of Magneto-Photoluminescence from InSb/InAs Quantum Dots

Circular-polarized magneto-photoluminescence of InSb/InAs type-II quantum dots has been investigated at a magnetic field applied in the Faraday geometry in the wide range of the excitation intensity. It was observed that under condition of the low excitation (similar to 1 mW in a spot of 1 mm diameter) luminescence from quantum dots is 100% polarized even at the moderate magnetic field of 4T. Increase of excitation results in diminishing polarization and even change of its sign at the power above similar to 100 mW. The effect is explained in terms of full electronic spin polarization in the conduction band due to the Zeeman effect in InAs matrix and power-dependent contribution into optical recombination of the pure heavy hole states or the combined heavy-light hole states emerged in InSb/InAs quantum dots.