硅基法布里--珀罗微腔室温发光特性的研究

Light emitting devices are the key to realize Si-based optic-electro integration. However, little progress has been made in improving the efficient light emission of Si-based material these years. The use of one-dimensional optical resonant cavity structures has been shown one of the effective methods to increase the output efficiency, and has created much interest recently. Planar microcavity effects on the spontaneous emission of porous silicon, silicon nanocrystal and Si/SiOx superlattices have been reported. The most widely researched Si-based microcavity is porous silicon cavity and has excellent emission feature (smallest width of emission up to date and very strong PL that can be seen with the naked eye), the resonant wavelength of the cavity blueshifts when it is exposed to the oxygen at ambient condition. When the cavity mode moves out of the stop band, the microcavity effect is missing. The microcavity in which Er3+ ions are embedded into the active layer needs high energy ion implantation (in order to pass through the top reflect mirror to reach the active layer) followed by high temperature annealing. The multiple-layered structure usually cannot stand the high temperature due to the difference of heat conductivities between the layers. In this project, we propose a novel structure of Si-based light emitting device which is compatible completely with Si IC technology. The theoretical analysis as well as experimental fabrication has been made. This device is fabricated by PECVD and its Bragg mirrors consist of a-SiO2:H/a-Si:H multilayers and the Fabry-Perot cavity is filled with a-SiCx:H film as the luminescence material. By designing the film thickness and refractive index of the luminescence material and Bragg mirrors, the device can emit strong, highly homochromatic visible light with a tunable wavelength under room temperature. Si-based vertical cavity light emitting devices that emit blue, green and red light are fabricated, tested and analyzed. The device that emits red light achieves a good performance: an emitting wavelength of 743nm, a peak intensity gain of 5 times over that of a-SiCx:H and a FWHM of 9nm. The green light device emits a light of 524.9nm with a FWHM of 19nm while the properties of blue light device are under measurement. Our work demonstrates that this easy-prepared and low cost whole Si-based light emitting device is of great important for electroluminescent devices and display application.

法布里--珀罗微腔是一种非常重要的新型量子效应光学微腔器件。本项目采用PECVD方法制傅墓?氮氧化硅结构作为微腔中的布拉格反射器，非晶碳化硅薄膜作为光发射层，通过对一维方向光子的限制，使发光层荧光强度增加，谱线变窄。调节发光层和反射器膜厚及折射率，可精确腔制发光峰位，因此该结构可望实现全硅基材料的强室温蓝光发射。.