硅衬底上锗硅合金光波导设计及工艺的优化考虑

报道用射频加热化学气相沉积法制备Ｓｉ／ＧｅＳｉ／Ｓｉ大断面单模脊形光波导中设计和工艺的进一步完善，ＧｅＳｉ合金层中Ｇｅ的含量Ｘ要满足脊形光波导是单模，光波导的数值，孔径接近单模光纤值，脊高小于临界厚度值等，计算表明兼顾上述三项要求应取ｘ＝１～３％，脊的高与宽受大断面及单模的制约。Ｓｉ的晶体结构使脊的二个腐蚀侧壁是斜坡，为此起始脊宽取５～６μｍ为宜；腐蚀液，抛光液的选取人保证脊则壁及波导面端的优良镜

The Optimization of Processes for Si Based GeSi Alloy Optical Waveguides

The optimization for fabricating large cross section Si/GeSi/Si single mode rib waveguides with RF heated CVD method is discussed. The optimal fraction x of Ge in GeSi layer defined by the necessity of single mode, numerical aperture and critical thickness is between 1～3%. The height and width of rib must be also limited by the single mode and large cross section, The etched rib side walls are slope due to the Si crystal structure. The best initial width of rib is 5～6 μm. The etching and polishing solutions must ensure the rib side walls and end faces to be mirror. The measured results show that the performance of the optical waveguides improred remarkably. The output light field is increased and the propagation losses is less than 0.5 dB/cm.