A characteristic feature of the amophous phase (a) is absence of long-range correlations which presence in the crystalline phase (c). Thus, a simple amorphous materials have only strong short-range ordering. For example, a lower limit of crystallize size c-Si is about 30-40 Å, but for an amorphous a-Si a upper limit on the correlation length is about 12-15 Å. Furthermore, in the amorphous phase the short-range structural order may be very different from that for crystals. An example is the GeTe compound. Here, c-GeTe have a local structure with tetrahedral local coordination, while a-Si have that with octahedral coordination. Therefore, in this case the new Raman lines are observed. Besides, the breakdown of selection rules and more broad range of allowed scattering process occurs. This introduces the appearance additional lines in Raman scattering spectra. The intensity of these lines are smaller than the main lines which are caused with crystalline phase. In finally, the amorphous materials show an strong broadening of the Raman mode which corresponds to the disordered state of the amorphous sample.

A characteristic feature of the amophous phase (a) is absence of long-range correlations which presence in the crystalline phase (c). Thus, a simple amorphous materials have only strong short-range ordering. For example, a lower limit of crystallize size c-Si is about 30-40 Å, but for an amorphous a-Si a upper limit on the correlation length is about 12-15 Å. Furthermore, in the amorphous phase the short-range structural order may be very different from that for crystals. An example is the GeTe compound. Here, c-GeTe have a local structure with tetrahedral local coordination, while a-Si have that with octahedral coordination. Therefore, in this case the new Raman lines are observed. Besides, the breakdown of selection rules and more broad range of allowed scattering process occurs. This introduces the appearance additional lines in Raman scattering spectra. The intensity of these lines are smaller than the main lines which are caused with crystalline phase. In finally, the amorphous materials show an strong broadening of the Raman mode which corresponds to the disordered state of the amorphous sample.

Raman spectra of amorphous materials have Boson peak.