Effect of photonic crystal stop-band on photoluminescence of $a$-Si$_{1-x}$C$_x$:H

Abstract

Effects associated with the change in the local density of photonic states in a periodic structure based on alternating \textit{a}-Si$_{1-x}$C$_x$:H and \textit{a}-SiO$_2$ amorphous layers forming a one-dimensional (1D) photonic crystal have been analyzed. The use of \textit{a}-Si$_{1-x}$C$_x$:H as the emitting material made it possible to examine the transformation of the photoluminescence spectrum contour that is comparable in width with the photonic stop-band. It was experimentally demonstrated that the emission is enhanced and suppressed in the vicinity of the stop-band. The relative intensities of the luminescence peaks at different edges of the stop-band vary with the detuning of the stop-band position and photoluminescence peak of a single \textit{a}-Si$_{1-x}$C$_x$:H film. The Purcell effect in the system under consideration was theoretically described by the method in which the local density of photonic states is calculated in terms of a 1D model. %A good agreement was obtained between the experimentally measured and calculated spectra. It was shown that the specific part of local density of states substantially increases at the long-wavelength (low-frequency) edge of the stop-band of a 1D photonic crystal as a result of the predominant localization of the electric field of the light wave in the spatial regions of \textit{a}-Si$_{1-x}$C$_x$:H which have a higher relative permittivity as compared with \textit{a}-SiO$_2$.