Self-organization of boxlike microstructures on GaAs (311)B surfaces by metalorganic vapor-phase epitaxy

We have found new self-organizing phenomena in metalorganic vapor-phase epitaxy of strained InGaAs/AlGaAs heterostructures on GaAs (311)B substrates. During growth interruption, strained InGaAs films naturally arrange into well-ordered arrays of nanoscale disks directly covered with AlGaAs. This self-organization has been observed in neither GaAs growth on (311)A substrates nor InGaAs growth on conventional (100) substrates. The disk diameter is controlled by the In content from 150 nm to 30 nm. These results clearly indicate that the strain energy of InGaAs films combined with the surface migration on (311)B surfaces causes the ordering of the microdisks. For the first time, our quantum-boxlike structures exhibit optical properties at room temperature comparable to conventional quantum wells.