Vg Instruments Group Limited

John J Parmenter

Paul R Stonestreet

Robert B Phillips

Method and apparatus for the deposition of material onto a substrate, the method comprising evaporating material from a source, controlling the dosage of material at the substrate by moving a shutter between an open position and a closed position, with a closing step comprising beginning to decelerate said shutter before reaching the closed position, subsequently thereby bringing the shutter substantially to rest at the closed position. Preferably the motion of the shutter is substantially harmonic with the acceleration of the shutter being directed towards, and proportional to the distance of the shutter from, the point mid-way between the open and closed positions. Contamination is reduced from prior methods and the invention is especially advantageous in molecular beam epitaxy.

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Crawley, United Kingdom

John J Parmenter