Sources used in molecular beam epitaxy
First Claim
1. A molecular or atomic beam source for molecular beam epitaxy comprising a hollow crucible having an open end and a closed end, at least one substantially self-supporting heating element heating said crucible disposed outside of and spaced apart from said crucible, and electrical supply leads to enable electrical current to be passed through each heating element, each heating element being supported by means of insulated electrically conductive supporting means only at the closed end of said crucible, each heating element comprising at least one pair of thin elongate metal strips extending substantially parallel to the axis of said crucible and disposed to present a major surface to the wall of said crucible, the strips of each pair being connected at the open end of said crucible by an electrically conductive link, and each of said strips being folded along one or more lines parallel to its longest edge in order to increase its resistance to bending.
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Accused Products
Abstract
A molecular or atomic beam source for use in molecular beam epitaxy comprises a hollow cylindrical crucible, preferably made of boron nitride, which is heated by an electric current passed through a plurality of very thin elongate metal strips disposed outside of and spaced apart from said crucible and mounted parallel to its axis. In order to maintain the strips in the correct position irrespective of temperature, they may be mounted on springs at each end, but preferably they are made in self supporting pairs linked at the open end of the crucible and mounted on brackets at the other end. The thin strips can be made self supporting by folding along lines parallel to their long axis in a variety of ways. They are arranged to present a large surface area to the crucible which ensures efficient heating and increases the maximum operating temperature of the source. The links between strips at the open end of the crucible can be made from the same material as the strips so that they provide additional heat at the open end of the crucible. This allows the crucible to be operated at higher temperatures than conventional sources and permits higher intensity molecular beams to be produced with true Knusden type evaporation. Therefore the source can also be used to produce beams from high melting point materials such as iron and silicon, as well as more usual materials such as galium, arsenic and phosphorus.
23 Citations
12 Claims
- 1. A molecular or atomic beam source for molecular beam epitaxy comprising a hollow crucible having an open end and a closed end, at least one substantially self-supporting heating element heating said crucible disposed outside of and spaced apart from said crucible, and electrical supply leads to enable electrical current to be passed through each heating element, each heating element being supported by means of insulated electrically conductive supporting means only at the closed end of said crucible, each heating element comprising at least one pair of thin elongate metal strips extending substantially parallel to the axis of said crucible and disposed to present a major surface to the wall of said crucible, the strips of each pair being connected at the open end of said crucible by an electrically conductive link, and each of said strips being folded along one or more lines parallel to its longest edge in order to increase its resistance to bending.
Specification