Controlling Polarization of 1.55-µm Columnar InAs Quantum Dots with Highly Tensile-Strained InGaAsP Barriers on InP(001)

The optical polarization properties of columnar InAs quantum dots (QDs) on InP substrate grown by metalorganic vapor-phase epitaxy were investigated. The polarization of photoluminescence was found to strongly depend on the strain in QDs as well as the shape of QDs. We successfully changed the polarization properties from a transverse-electric-dominant to a transverse-magnetic-dominant regime by controlling the height of coupled QDs based on the stacking number and by controlling strain within QDs based on the thickness of 3.7%-tensile-strained barriers. Highly strained side barriers were required to change the polarization of QDs, which is considered to be due to wetting layers acting in maintaining biaxial-compressive strain in QDs. Polarization-insensitive QDs with the 1.55-µm telecom region were obtained, which promises to provide polarization-insensitive semiconductor optical amplifiers.