Vibrational spectroscopies: a natural mesoscope for the study of spontaneous ordering in alloys

The novel paradigm of a 1-bond2-mode percolation-type behavior for the lattice dynamics at the zone-centre of random semiconductor alloys, that mirrors a lattice relaxation of the similar 1-bond2-length type, opens an attractive area for a (re-)discussion of spontaneous long-range clustering/anticlustering in terms of purely intrinsic effects. As examples, we show in this work how such antagonist effects as CuPt type spontaneous ordering of InGaP2 and N-induced In-anticlustering far from N-impurities in (N,In)-dilute InGaAsN can be discussed/evidenced from the transverse optical vibration spectra. The whole discussion is supported by full contour modelling of the TO Raman lineshapes via our percolation model. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)