We describe a novel growth mode in a strained InGaAs system on a GaAs (311)B substrate, which surprisingly produces a very small confined nanostructure automatically during the growth interruption of metalorganic vapor phase epitaxy. We call this phenomenon self-organization, because it accompanied with pronounced ordering in mutual arrangements of nanocrystals. The important point is that built-in InGaAs strained quantum disks exhibit a strong photoluminescence emission, indicating that self-organization process may possibly produce nanostructures with a quality needed for optical devices.