Development Of Low Temperature Effusion Cell

Molecular Beam Epitaxy is one of the advanced technology in the development of new materials,which promotes the development of semiconductor devices basing on the microstructure material,expands the field of semiconductor science,widely applied to metal,insulators and the growth of the superconducting materials,and plays a huge role in basic research and industrial production.Ultra-high vacuum,sample substrate temperature control and the performance of Effusion Cell are the core of Molecular Beam Epitaxy.During the growth of superconducting material and semiconductor system,Effusion Cell,which can steam a variety of metals,is the main evaporator.The Effusion Cell should be completely in accordance with the ultra-high vacuum design standard to ensure the accurate control of the film composition;The Effusion Cell can be heated at high temperature to evaporate a variety of metals;It is required that the Effusion Cell temperature can be controlled accurately to achieve the stable growth of the film and the control of monatomic layer.At present,the research on low temperature Effusion Cell in China is still at the exploratory stage,and the technology has not been systematized yet.Low temperature Effusion Cell used in China is widely derived from abroad at present.Therefore,a low temperature Effusion Cell for alkali metals,high vapor pressure metals,organic evaporation in vacuum environment has been developed based on the comprehensive analysis of the structural characteristics and advantages of the international advanced Effusion CellThis paper presents a general design scheme for the low temperature Effusion Cell based on the theoretical calculation and structural requirements which includes heating device,cooling device,temperature measuring device,and connection device.According to the requirement of vacuum environment,analyze the material selection of each part,and then established the evaporation and cooling device simulation model.Control the presence of cooling water cover and shielding cover,and analysis crucible internal temperature changes under the different condition by Mutiphysics module of ANSYS simulation software,which verifies that the cooling water has the cooling effect to the crucible.According to the requirements of the vacuum system,a small vacuum system experimental platform is set up to test the performance of the low temperature Effusion Cell.Experimental results show that the beam of Effusion Cell stability,film coating uniformly,evaporation temperature is continuously adjustable between 80~1000?.Molecular Beam Epitaxy Effusion Cell temperature error is less than 1 ? and it can quickly reach stable state,meet the requirements of the indicators of Molecular Beam Epitaxy Effusion Cell.The Effusion Cell can evaporate most metals and work steadily at lower temperatures,especiallyfor the evaporation of high vapor pressure metals.The successful research and development of this low temperature Effusion Cell has accumulated design technology experiences for the field of vacuum equipment in China,which is of great significance for promoting the independent innovation of the Effusion Cell industry.