Structural and vibrational properties of amorphous phosphorus

Thin films of amorphous P, prepared by rf sputter deposition under conditions of variable substrate temperature, have been studied using x-ray diffraction and Raman scattering methods. The low-angle x-ray spectra indicate a peak at k1.1 ^-1, whose half-width and relative intensity are a continuous function of deposition temperature. The diffraction spectra provide evidence for continuously variable intermediate-range order as a function of deposition temperature. The polarized and depolarized Raman components indicate substantial changes with deposition temperature associated with the development of a number of high-frequency spectral features. Modifications of the depolarized Raman spectra, as well as differences between the phonon density of states and depolarized bulk spectra, provide additional evidence for intermediate-range order. The x-ray and Raman spectra imply structural and dynamical correlations in amorphous solids of intermediate range and further suggest that such correlations are continuously variable. The experimental results are discussed in terms of a layerlike model with variable intralayer and interlayer correlations. As in crystalline solids, it appears that structural correlations are a prerequisite for dynamical correlations for optical-like modes.