Physical properties of highly uniform InGaAs pyramidal quantum dots with GaAs barriers: Fine structure splitting in pre-patterned substrates

InGaAs Quantum Dots embedded in GaAs barriers, grown in inverted tetrahedral recesses of 7 {\mu}m edge, have showed interesting characteristics in terms of uniformity and spectral narrowness of the emission. In this paper we present a study on the fine structure splitting (FSS). The investigation of about 40 single quantum dots revealed two main points: (1) the values of this parameter are very similar from dot to dot, proving again the uniformity of Pyramidal QD properties, (2) there is a little chance, in the sample investigated, to find a dot with natural zero splitting, but the values found (the mean being 13 {\mu}eV) should always guarantee the capability of restoring the degeneracy with some corrective technique (e.g. application of a small magnetic field).