Magnetooptical investigations of single self assembled In0.3Ga0.7As quantum dots

We present results from magnetooptical investigations of large elongated single self assembled In0.3Ga0.7As quantum dots with a low surface density of 3×109cm-2. Compared to conventional In0.6Ga0.4As quantum dots the dimension of the investigated dots is enlarged by nearly one order of magnitude using a low strain In0.3Ga0.7As nucleation layer. In addition, the exciton exhibits a smaller g-factor of 0–0.4 and a larger diamagnetic coefficient of 20–32.8μeVT-2 in Faraday geometry, reflecting the increased extension of the exciton wavefunction, with respect to In0.6Ga0.4As quantum dots. From power dependent investigations we observe biexciton binding energies ranging from 1.7 to 1.9 meV. Excited state emission appears typically 2–5 meV above the ground state which is consistent with the increased dimensions of the structure. Furthermore we find linear polarization degrees of up to 0.6 from exciton emission of the elongated quantum dot structure.