Extinction spectra in the range 100–700 nm of sputtered films of hydrogenated amorphous silicon, prepared under different conditions, have been obtained at room temperature and at 80 K. The extinction spectra of inhomogeneous samples show the presence of anomalous dips in the range 100–200 nm. These minima can be explained in terms of light interference effects among regions of an inhomogeneous film having random fluctuations of the refractive index, which are assumed to have a particular probability distribution. The data are discussed on the basis of the calculated light transmission through a random medium. The measurements suggest the possibility of an amorphous equivalent to photon crystals.

• Received 27 May 1993

DOI:https://doi.org/10.1103/PhysRevB.48.12292