Lateral localization of optical phonons in GaAs quantum islands

Lateral localization of phonons in GaAs islands formed on the (100) surface under conditions of (2x4) structural reconstruction is detected by means o f Raman scattering. The triplet structure of the peak corresponding to late rally localized phonons is detected in the Raman scattering spectra of a Ga As0.6/AlAs5 sublattice grown by molecular-beam epitaxy. The distribution of islands over different configurations is determined by comparing the theor etical Raman scattering spectra, calculated in the Vol'kenshtein bond polar izability approximation, with the experimental spectra. The atomic configur ation of the islands is identical to the results obtained previously by sca nning tunneling microscopy. According to the calculation, 70% of the island s contain fewer than 18 Ga atoms, and lateral localization occurs with AlAs barrier thickness of 2 or more monolayers. (C) 1999 American Institute of Physics. [S0021-3640(99)00314-X].