The influence of the strain on the dot morphology of GaInAs quantum dots has been investigated. The strain was varied by the In content in GaInAs/GaAs quantum dots from 60% down to 30% by keeping the emission wavelength at about 900 nm at 10 K. Spectral properties are compared with morphological results determined by scanning electron and scanning transmission electron microscopy confirming a change of the dot geometry from circular to elongated shapes during an overgrowth process. These lowly strained quantum dot layers with enlarged dot sizes exhibit a reduced dot density of 6-9 x 10(9) cm(-2) and a strongly enhanced oscillator strength, which make them very interesting for single quantum dot and cavity quantum electrodynamic experiments as well as for applications like single photon emitters. (c) 2005 Elsevier B.V. All rights reserved.