The silicon-based materials

such as silicon nitride

silicon carbide and silicon oxide

etc

have been studied extensively both for their optical and electric characteristics.Especially

the luminescent be-haviors have been attracting much attention in order to develop Si-based light emitting diodes and even laser.Recently

strong blue to red light emission have been observed in amorphous silicon nitride in some reports.Also the photoluminescence and electroluminescence of silicon oxide have been realized and the silicon-based optical gain was also demonstrated.In this report

the optical characteristics of a series of amorphous silicon carbide films with different ratio of carbon to silicon have been studied.The ratio is controlled by changing the gas ratio(

R

)of methane to silane from 2 to 15

which resulted in different bonding configurations

microstructures and different optical characteristics

such as luminescence behavior and refraction index.Photoluminescence excited by Ar

+

488 nm laser and by the continuous wavelength xenon lamp

FTIR and Raman scattering have been used to analyze and explain the character and the micro structure of the films.It was found that the strong luminescence can be observed for samples deposited at

R

<

10.The luminescence peak and intensity was obviously changed after step by step steady-furnace-annealing from 400℃ to 800℃.The Gaussian-simulation indicated that two luminescence bands appear in all the spectra for the samples annealed at the different temperatures and their intensities were changed with the annealing temperature.This illustrated the transformation of the microstructure of the films at different annealing temperatures.The luminescence can be related to the radiative recombination of the electron-holes in the localized tail states which are excited in the extended states.The blue light emission can be found for samples deposited at R

>

10 and the luminescence intensity was enhanced after post-annealing under UV light excitation.Based on the optical properties of a-SiC films

all a-SiC film based optical microcavities were designed and prepared by controlling the thickness and composition of a-SiC films.The resonant enhancement of luminescence band at 650 nm was achieved and the luminescence band was significantly narrowed.The modulation effect due to the existence of micro-cavity was demonstrated.The present results revealed the possibility to realize the solid state microcavity light emitting diodes.