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分子束外延材料的质量强烈地依赖于分子束外延生长时环境气氛(主要是碳氧气氛).尽量地减少碳.氧对外延膜的污染,提高外延生长时的真空度对高质量外延膜的生长十分重要.针对国产分子束外延Ⅲ型设备在材料外延生长时与国外同类设备相比真空度不好,碳、氧污染比较严重的问题,利用低温泵对有害气体(水蒸汽、CO_2、CO)具有巨大的抽速、较高的极限真空、安装、维护简便等优点,在国内首次将低温泵和离子泵的组台抽气运用于分子束外延材料生长实验.实验结果表明:低温泵与离子泵组合抽气提高了生长时的真空度,降低了 H_2O、CO_2,CO 等气体的分压.外延材料碳、氧污染明显降低.外延材料的性能得到改善.众多实验结果表明:在国产设备上利用低温泵与离子泵组合抽气进行分子束外延材料生长的尝试是有效的、成功的.同时,为新一代分子束外延设备的真空系统设计及工艺改进进行了有益的探讨.
The quality of molecular beam epitaxy depends strongly on the ambient atmosphere (mainly the carbon-oxygen atmosphere) during molecular beam epitaxy, minimizing the carbon and oxygen contamination of the epitaxial film and increasing the degree of vacuum during epitaxial growth. In order to deal with the problem that the domestic molecular beam epitaxy type Ⅲ equipment is not good in vacuum degree and carbon and oxygen pollution are serious compared with foreign similar equipment when the material is epitaxy, the cryogenic pump is used to treat the harmful gas (water vapor, CO 2, CO ) Has the advantages of huge pumping speed, high ultimate vacuum, easy installation and maintenance, etc. It is the first time in China to apply the pump of the cryogenic pump and the ion pump to the molecular beam epitaxy material growth experiment.The experimental results show that the cryogenic pump and The combination of ion pump and pump can increase the vacuum degree during growth and decrease the partial pressure of H 2 O, CO 2 and CO, etc. The carbon and oxygen pollution of the epitaxial material decreases obviously.The performance of the epitaxial material is improved.Many experimental results show that in the domestic equipment On the use of cryogenic pump and ion pump combined extraction of molecular beam epitaxy material growth attempt is effective and successful.At the same time, a new generation of molecular beam epitaxy equipment vacuum System design and process improvement for a useful discussion.