| 摘要 |
A valve for an effusion cell is disclosed. The valve includes a valve seat having an opening in communication with an interior chamber of a heating crucible. A disk-shaped valve member is axially movable with respect to the valve seat in order to increase or decrease the effective size of the valve seat opening. An outlet nozzle may be provided downstream from the valve seat. The valve provides mechanical adjustment of the deposition rate of the evaporated material replacing thermal changes as the means to control the deposition rate or flux from the effusion cell. The nozzle, valve disk and valve seat may be made of machined graphite coated with a carbon-containing material such as pyrolytic graphite, silicon carbide, or the like. The effusion cell may be used for molecular beam epitaxial growth of various materials incorporating mechanical control of the flux without negatively impacting the state of the art qualities of the deposited films with respect to deposition uniformity, surface morphology and background doping.
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