非晶碳化硅材料与光学微腔的制备与发光

Preparation and Luminescence of Amorphous SiC Material and Its Optical Microcavity

利用等离子体化学气相沉积技术在100℃的衬底温度下,制备了具有不同组分比的系列非晶碳化硅薄膜。结合傅里叶变换红外光谱与喇曼光谱对所制备的薄膜微结构进行了表征与分析,同时,对具有不同组分比的非晶碳化硅薄膜室温光致发光性质进行了系统的研究。结果表明在Ar+离子激光和Xe灯紫外光的激发下,不同组分的样品显示出不同的光致发光特性,并对样品的发光特性与其微结构的联系进行了讨论。在此基础上,用碳化硅薄膜设计和制备了全固体光学微腔,研究了微腔对碳化硅发光行为的调制作用。

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 behaviors 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 microstmcture 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.